摘要:

RUHEMAKN AND HEMMY : ,&KETONIC ACIDS. 329 XXXT.--Co12tribittio?zs to the Jin02dedgc o,f the p-ketonic Acids. Part IV. By SIEGFRIED RUHEMANN, Ph.D., M.A., and A. S. HEMMY, B.A., M.Sc., Hutchinson Student of St. John's College, THE starting point of the experiments recorded in this paper has been the study of the interaction of ethylic chlorofumarate and ethylic chlorocrotonate with ethereal salts of P-ketonic acids. The products formed, as shown in the previous paper, are regarded as ketonic com- pounds, in spite of the fact that their aIcoholic solutions are not coloured by ferric chloride, or only faintly so. Ethylic acetosuccinate, also, according t o Conrad's statement (Ann., 1877, 188, 218) does not give a colour-reaction with the ferric salt. I n the hope of arriving a t an explanation of the difference in the behaviour of the ethereal salts which have t o be regarded as ketonic compounds, we have subjectec' ethylic acetosuccinate to a more careful investigation.The ethereal salt was prepared a t first by adding to a solution of sodium in alcohol the calculated quantities of ethylic acetoacetate and chloracetate, and boiling the mixture for about 2 hours. The ethereal salt, which was separated in the usual manner, boiled at 134-135-5" under a pressure of 8 mm., but we found that the330 RUHEMANN AND HEMMY: CONTRIBUTIONS TO THE yield was unsatisfactory, and i t was necessary to fractionate it re- peatedly in order to get a product of fairly constant boiling point. This induced us to use Conrad's method, namely, adding the calculated quantity of sodium to a benzene solution of ethylic acetoacetate, and, after the metal had disappeared, boiling the product with the required amount of ethylic chloracetate.The greater portion of the ethereal salt formed in the reaction boiled at 135.5-136" under a pressure of 8 mrn. The third method which we employed appears to us the most satis- i actory. The calculated quantity of sodium (I 1 *5 grams), dissolved in alcohol, was mixed with ethylic acetoacetate (65 grams), the solution evaporated to dryness in a vacuum, and the solid residue boiled for 2 hours on a water bath with dry benzene after adding the ethylic chloracetate (62 grams). The benzene was then distilled off, the residue poured into water, and the ethereal salt extracted with ether; the oil remaining after evaporation of the ether was distilled under diminished pressure, and in this way 62 grams of pure ethylic aceto- succinate boiling a t 133-134" (at 8 mm.) was obtained.The com- pound, by whatever method obtained, gives a most marked red-violet coloration on adding ferric chloride to its alcoholic solution. The molecular refraction n2-1 - - calculated from the density, which was found to be d 16"/16" = 1.087, and the refractive index : rltD = 1,438, amounts to 52.17 whilst the formula n2+2 cl CH,°CO*cH<CH,.CO(iC,HS COOC,H- requires 52.05. This constitution is in full agreement with the results of the in- vestigations undertaken by various workers, and is also supported by the following experiments. Action of Anamornia on Ethylic Acetosuccinate. Emery (Annalen, 1890, 260, 137) has already subjected this ethereal salt to the action of ammonia and primary amines; using an absolute alcohol solution of ammonia, he obta,ined a compound which he characterised as a lactam of the formula CH,* $! = $!*COOC,H, NH CH, \ / If, however, ethylic acetosuccinate is allowed to remain in contact with a strong aqueous solution of ammonia for 24 hours at the ordinary temperature, it disappears, the liquid turns green, thenKNOWLEDGE OF THE ,&KETONIC ACIDS.3.31 brown, and a white solid separates; this dissolves readily in boil- ing water, and, on cooling, crystallises out. in colourless needles, which do not melt, but begin to decompose at about 250". The following analytical data correspond with the formula CH,* f: 7-CONH, NH CH., \/ co 0,2096 gave 0.3928 CO, and 0.1090 H,O.0.2590 ,, C=51.11; H= 5.77. 455 C.C. moist nitrogen at 20" and 753 mm. ; N = 19.93. C,H,N20, requires C = 51.42 ; H = 5.71 ; N = 20 per cent. The compound is, therefore, to be regarded as the lactam of amido- ethylidenesuccinamide. Potash readily dissolves it, and, on boiling the solution, ammonia is evolved, but this ceases after about an hour's heating. The liquid, when acidified with hydrochloric acid, repeatedly extracted with ether, and the ether evaporated, yields colourless plates which, after recrystallisation from water, melt at 186" and show all the properties of succinic acid. The analysis of its silver salt gave, more- over, 65-22 per cent. Ag, as compared with the theoretical value, 65.06.From this it follows that the ring is unstable, and under the influence of potash the compound suffers a decomposition with formation of succinic acid. On boiling ethylic acetosuccinate with aniline, a decomposition takes place similar to that which occurs in the case of ethylic acetoacetate (Oppenheim and Prechl, Ber., 1876, 9, 1098) giving rise to the forma- tion of diphenylcarbamide. This was identified by the melting point (238"), and by a nitrogen determination which gave 13-31 instead of 13.20 per cent. nitrogen as required by theory. Action of PhenyZhydm&ne o n Ethylic Acetosuccinate. Hydrazine hydrate, as found by Curtius (J. pr. Chem., 1894, 50, 518), acts on the ethereal salt, forming ethylic methylpyrazolone- acetate. Phenylhydrazine behaves in like manner, yielding first the phenylhydrazone which, on raising the temperature, loses alcohol and becomes a derivative of pyrazolone.A mixture of equivalent quantities of the ethereal salt and phenyl- hydrazine gradually solidifies to a hard mass. This is powdered, washed with dilute spirit, dissolved in warm alcohol, and water added until the solution becomes turbid, when colourless needles separate ; these melt at 84--85O, and art3 sparingly soluble in ether but readily in alcohol. The analytical data correspond with the formula332 RUHEMANN AND HEMMT: CONTRIBUTIONS TO THE CH,* g YH*CH,* COOC,H, N*NH*C,H,* COOC,H, for the phenylhydrazone of ethylic acetosuccinate. 0.2035 gave 0.4650 CO, and 0.1320 H,O. 0.2284 ,, C,,H,,N,O, reqnires C = 62.74 ; H = 7.1 9 ; N = 9.15 per cent, On heating the phenylhydrazone gradually to 170" in an oil bath, alcohol distils over, and a brown oil is left which solidifies on cooling, The product separates from its solution in dilute alcohol in coluurless, glistening plates, which melt a t 139-140", and are readily soluble in alkali.On analysis, numbers were obtained which agree with the formula C = 62.76 ; H = 7 21. 17 C.C. moist nitrogen at 7" and 765 mm. ; N = 9-29. CH,* - FH*CH2- COOC2H, N co for ethylic 1 -phenyl-3-me t h yl-5 - p yrazolone- 4-ace tat e. 0.2087 gave 0.4935 CO, and 0.1170 H,O. C = 64.49 ; H = 6.22. 0.2255 ,, 20.5 C.C. moist nitrogen at 11" and 765 mm. ; N=10*91. C,,H1,N,O3 requires C = 64-61 ; H= 6.15 ; N= 10.77 per cent. On boiling the solution of the ethereal salt with concentrated potash for about 2 hours, it is hydrolysed, and on adding hydrochloric acid to the red alkaline liquid, the organic acid is precipitated.This crys- tallises from boiling water in colourless, silky prisms containing water of crystallisation which they lose at looo, becoming opaque. It softens a t about 170" and melts at 180" with evolution of gas. A nitrogen determination of the acid dried at 100" gave the following result, which corresponds with the formula for the phenglmethylpyrazolone- acetic acid : 0-2300 gave 24.5 C.C. moist nitrogen at 18" and ,754 mm. N = 12.20. The air-dried crystals contain 1H,O. 0.3020 lost, a t 100", 0.0220. C,,HI2N,O, requires N = 1 2 -07 per cent. H,O= 7.28. C,,H,,N,O,,H,O requires H,O = 7-20 per cent, Action of Byomine on Ethylic A cetosuccinute.The study of the action of bromine on ethylic acetomethylacetate led to the result that the halogen enters into the y-position and yields a compound of the formula CH,Br*CO*CH(CH,)*COOC,H5 (Roubleff, Aiznulen, 1890, 259, 261 ; Hantzsch, ibid., lS90, 266, 90). This ethereal salt, on heating, loses ethylic bromide with formationKNOWLEDGE OF THE 6-KETOEIC ACIDS. 333 of tetrinic acid (a-methyltetronic acid), which has lately been subjected to a closer investigation by L. Wolff (Anncclen, 1895, 288, 11). He showed that the acid is to be represented by the formula YO* CH, CH,* CH-C>*' which mas first suggested by Michael (J. p. Chern., 1888, 37, 502). Similar to the transformation of ethylic bromacetoruethylacetate is that of the bromo-derivative of ethylic acetosuccinate, giving rise t o the formation of ethylic carbotetrinate, which had already been obtained by Moscheles and Cornelius (Be].., 1888, 21, 2603).We have repeated these experiments, as the bromo-derivative of ethylic acetosuccinate had not been analysed, and we are able to confirm their observation as to the formation of ethylic carbotetrinate, which is formed on distilling the bromo-derivative under diminished pressure. The ethereal salt of the bromo-acid is obtained on adding the calcu- lated quantity of bromine to the solution of ethylic acetosuccinate in chloroform, and subsequently evaporating. The oil, after having been left in a vacuum over potash and sulphuric acid for some time, was analysed, the results agreeing with the formula CH,.COOC,H, CH,Br* CO*CHH<CooC. H 2 5 0.3833 gave 0.2458 AgBr. The density was found to be cZ 15"/15" = 1.3854. On distilling the bromo-compound under diminished pressure, it decomposes, and an oil distils over a t 191-198" (at 14 mm.). This soon solidifies, and, on crystallisation from benzene, separates in colourless plates melting a t 96-97". It is readily soluble in alcohol, but only sparingly in ether. The results of analysis agree with the formula for ethylic carbo- tetrinate : Br = 27.29. CloH15Br0, requires Br = 27.12 per cent. FH2* CO* YH* CH,* COOC,H, O-- - co 0.2163 gave O*412lhC0, and 0.1086 H,O. C = 51.96 ; H = 5.5'7. C,H,,O, requires C =51.61 ; H=5.38 per cent. The aqueous solution of this ethereal salt reddens litmus paper, reduces ammoniacal silver nitrate, and is coloured red by ferric chloride.Ethplic Benxoy Isucciw ate. This compound has been obtained by W. H. Perkin, jun. (Trans., 1885, 47, 272), by the interaction of the sodium compound of ethylic benzoylacetnte and ethylic chloracetate. He states that the ethereal VOL. LXXI. A A334 RUHEMANN AND HEMMY: CONTRIBUTIONS TO THE salt thus prepared suffers decomposition when distilled under diminished pressure, unless the operation is carried out rapidly with small quantities of substance ; we find, however, that it boils without any decomposition if the operation be conducted a t a very low pressure. It is a yellow oil, which distils at 192-193" under a pressure of 10 mm., has the density d 14"/14"=1-1404, and, in alcoholic solution, gives a red coloration with ferric chloride.0.2215 gave 0.4256 CO, and 0.1350 H,O. C = 64-72 ; H = 6.77. C1,H1,O, requires C = 64-75 ; H = 6.47 per cent. According to the result of the chemical investigation of ketonic compounds by Claisen, which have been supported by Briihl's refracto- metric researches, ethylic beuzoyhccinate should be represented by the C,H,* C(oH):C<C~,.~~()C,H,, Cooc2H, and this agrees with the refractometric behaviour of the ethereal salt. The refractive index was n2 - ,lM, n + 2d found t o be m,=1-1404 a t 16". therefore, is 72.62 whilst the above formula requires 72.72. Ethylic benzoylsuccinate, when allowed t o remain in contact with strong aqueous ammonia, gradually disappears, and the dark liquid deposits coloured crystals ; these dissolve in boiling water, and, after decolorising the solution with animal charcoal, crystallise in colourless needles which were identified as succinimide by a comparison with a specimen prepared from ethylic succinate, and by a nitrogen determi- nation, 0.2102 gave 44 C.C. moist nitrogen at 19" and 763 mm. N=24*20. C,H,N,O, requires N = 24.14 per cent. Ethylic benzoylsuccinate, therefore, under the influence of ammonia, undergoes a decomposition similar to that which takes place on boiling it with baryta water (compare Perkin, Zoc. cit.). The molecular r e f r a c t i o n , T GONVILLE AND CAIUS COLLEGE, C-4MBRIDGE.

ISSN:0368-1645    

DOI:10.1039/CT8977100329

出版商:RSC    

年代:1897

数据来源: RSC

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334 RUHEMANN AND HEMMY: CONTRIBUTIONS TO THE XXXI1.-Coiitribzctions to the Knowledge of the ,@-ketonic Acids. Purt I? By SIEGFRIED RUHEMANN, Ph.D., &!.A,, and A. S. HENNY, B. A., KSc. IN the course of further research on the behnviour of ethylic chloro- fumarate and ethylic a-chlorocrotonate towards the ethereal salts of P-ketonic acids, me have met with compounds which claim a specialKNOWLEDGE OF THE P-KETONIC ACIDS. 335 interest, and, although the experiments have not yet been concluded, we think it advisable to communicate the results already obtained. To a solution of 3.8 grams of sodium in 100 C.C. of absolute alcohol, 30.4 grams of ethylic oxalacetate are added, and the sodium compound thus formed is mixed with 33.4 grams of ethylic chlorofumarate ; on digesting the mixture for about 2 hours on a water bath, the whole dissolves to a deep blue solution, without any sodium chloride being deposited.The residue left on distilling off the alcohol is neutral to litmus, and when treated with water deposits an oil containing un- changed ethylic chlorofumarate ; this can be removed by agitation with ether. When hydrochloric acid in excess is added to the blue aqueous solution thus obtained, the colour becomes paler, but does not com- pletely disappear until after the lapse of a considerable time. At the same time, the acid precipitates an oil and a solid substance, which can be easily separated, as the former dissolves readily in ether, whereas the latter, being almost insoluble, remains suspended in the ethereal as well as in the aqueous solution; it is collected on a filter and washed with water.The white substance thus obtained dissolves in dilute alkali, producing a blue solution, the colour of which rapidly disappears if ex- cess of the reagent is added. On warming the substance with water o r alcohol, a trace of it dissolves, and the blue colour again appears, but disappears slowly on the addition of hydrochloric acid. The compound, therefore, has strong acid properties, and forms a blue salt with the alkali contained in the silicate, which the solvents extract from the glass. The behaviour of the substance towards alkalis shows evidently an analogy with phenolphthalein. On carefully warming the solid with glacial acetic acid, it dissolves (prolonged heating causes decomposition), and on cooling crystallises out in colourless needles, the solution again being of a deep blue colour, due undoubtedly to the alkali dissolved out of the glass. The crystals, washed with water to remove the coloured mother liquor, and dried first in a vacuum and then a t loo", melted and decomposed a t 200°, and on analysis gave numbers corresponding with the formula CI,H,,O,.0.2379 gave 0.4690 CO, and 0.1047 H,O. C = 53-76 ; H = 4.89. 0.2120 ,, 0.4185 CO, ,, 0.0975 H20. C=53*S3; H=5.11. 0.2156 ,, 0.4250 CO, ,, 0.1017 H,O. C=53*76 ; H= 5.24- C,,H160, requires C = 53.84 ; H = 5.12 per cent. Besides this compound, another is formed isomeric with it; this I s contained in the oil which separates from the blue solution along with the above-mentioned white solid.The ethereal extract containing this oil deposits crystals on standing for a day in a vacuum. These, after being freed from adhering oil by filtration and washing with dilute A A 2336 RUHEMAEN AND HEMMY : ,@-KETONIC ACIDS. spirit, are crgstallised from alcohol, when they are obtained in colour- less needles melting at 1 2 3'. 0.2140 gave 0.4225 GO, and 0.1055 H20. C = 53-81 ; H = 5.46. 0.2199 ,, 0,4350 GO, ,, 0.1040 H20, C = 53'94 ; H = 5-25. C,,H,,O, requires C = 53.84 ; H = 5.12 per cent. This compound differs from its isomeride, not merely in its melting point, but also in its chemical behaviour ; it dissolves in dilute alkali, but without any coloration; ferric chloride added to the alcoholic solution colours it reddish-brown, whilst the isomeride melting a t 200' gives a slight coloration with the ferric salt only after standing for some time.The facts that the ethylic chlorofumarate is hardly attacked, and that no sodium chloride separates, point to the view that ethylic oxalacetate alone takes part in the formation of these two isomerides. I n fact, Claisen and Hori (Be?.., 1891, 24, 120) observed in the formation of the triethylic salt of aconityloxalic acid from ethylic oxalacetate a blue coloration of the liquid, which they attributed to a salt of another condensation product of the latter substance; they did not, however, further investigate the matter. The formation of the two isomerides may without difficulty be explained by assuming that 2 mols. of ethylic oxalacetate unite with the loss of 1 mol.of water and 1 of alcohol, and we may suppose that the formation of the compound decomposing at 200' takes place in the following manner. This substance is accordingly to be regarded as triethylic anhydro- oxnlaconitate, and we may explain the coloured salts derived from it as formed by displacement of the hydrogen of the hydroxyl group by metal; whilst the decolorisation of the blue solutions with excess of alkali may be considered to be brought about by the scission of the ring and formation of salts of ethylic aconityloxalate. I n a similar way, the formation of the isomeride melting a t 123O may be accounted for as follows. This compound may therefore be represented as ethylic pyronetri- carboxylate, and this view is supported by the similarity of its behaviour to that of pyrone.RAY: THE NITRITES OF MERCURY, ETC. 33’7 We are occupied with the fnrther study of these isomerides and with the working out of methods of production which will give better yields than those described above. GONVILLE ANl) CAWS COLLEGE, CANBRIDGE.

ISSN:0368-1645    

DOI:10.1039/CT8977100334

出版商:RSC    

年代:1897

数据来源: RSC

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RAY: THE NITRITES OF MERCURY, ETC. 337 XXXIK-The itTitrites of Memzcy cmcl the Varying Conditions uiadey which they cwe formed. By P. C. RAY, D.Sc. (Edin.). Hemu~ous Nit~ite," Hg,(NO,),. IN an earlier paper 9 on the preparation of the above salt, I said that 66yellow nitric acid of sp. gr. 1.410 is diluted with water in the proportion of 1 t o 3 ; a large excess of mercury is at once poured into the liquid, the heat of solution of the acid in water helps to start the reaction." This has since been repeated several times, and I have found that colour- lessnitric acid acts just as well, and that it is better to dilute it in the proportion of 1 to 4 ; in other words, dilute nitric acid containing 13 to 14 per cent. N,O, seems to be most favourable for tbe growth of the yellow, thin needles and prisms.For the results of analyses, see A I, 11, Table, p. 345. Nethod of Astcclgsis. Estinmtion of Mewury.--The mercury which separates out on gently heating the salt with water has been termed " free " mercury ; that contained in the clear solution in the rnemuvous state was thrown down as chloride by means of sodium chloride, and that existing in the filtrate in the mercuric form was estimated as sulphide. For details, see Zoc. cit., p. 267. Sometimes the free mercury comes out too low ; this is due chiefly to imperfect coagulation of the grey powder and loss by volatilisation. As a further check, some of the salt was dissolved in the minimum amount of strong nitric acid, sodium chloride was added t o the solu- tion, and the precipitated calomel was redissolved in aqua regia, and the total mercury precipitated as snlphide. For result of this analysis and the formula, &c., see A 111, Table, p. 345.I n the memoir referred to above, the mercury in the mercuric salt was generally thrown down as calomel by the addition of phosphorous acid; this method invariably gave too low results, in fact 30.7 was * Compare Divers and Haga, Trans., 1887, 41, p. 49. t Zeit. anorg. Chem., 1896, 12, 365, (from Journal Asiatic Society Bengal, 1896, lxv., ii, No. 1).338 R ~ ~ Y : THE NITRITES OF MERCURY AND THE VARYING taken as the mean percentage of mercury both in the " free " state as also in the mercuric salt ; in only one instance was the mercuric mercury estimated as sulphide, and this gave 31.33 as the percentage (Zoc.cit.). I naturally gave preference to the number 30.7, and mas thus misled into assigning the formula Hg,(NO,), + H,O to the salt. I have, how- ever, since then succeeded in preparing a hydrated salt of this formula, which will be described later on. Estinmtion of the iJTits.ogen.-As stated in the first paper, the nitrogen was estimated by the Crum-Frankland method. Determinations of nitrogen by the direct method, however, seemed highly desirable, especially as the various basic nitrites and nitrates to be subsequently described are but sparingly soluble in water, and are only partially decomposed on treatment with an alkali; conse- quently, the total nitrogen cannot be obtained in the soluble form. The method employed was that of Dumas, somewhat simplified.The salt was placed in a porcelain boat in a combustion tube and the whole length of the tube between the boat and the delivery tube was closely packed with bright copper foil, well-dried magnesite being used for the supply of carbonic anhydride. This method bad the additional advan- tage that the various stages of decomposition of tho salts could be watched, and also that it was easy to see whether water was given OB from them." For analytical data, see A 11, Table, p. 345. Foi*mation of the firitrite us Dependent o n the 8ts.ength of the Acid. A. Nitvie acid (1 : 4)-It has already been pointed out that the acid (sp. gr. 1.41) diluted in the proportion of 1 to 4 of water favours the growth of the yellow needles and prisms. It was, however, thought desirable to systematically study the conditions under which the nitrites are formed.With this acid (1 : 4), the needles begin to appearin the course of about half an hour, and at the end of 24 hours a considerable crop is obtained. As, however, the crop thus formed on the surface of the mercury acts as a protective layer, thereby hindering the action of the liquid on the metal, the salt ceases to grow; the deposit of the nitrite, thereFore, should be removed, and the mercury and liquid carefully decanted off into another beaker, when a second crop will be obtained the next day. By repeating the process, successive crops can be col- lected from day to day. B. Nitric acid (1 : 6).-The first crop of crystals of mercurous nitrite was collected next day, and two others at intervals of 5 days, but a * I avail myself of this opportunity to express my sincere thanks to Mr.N, Chandra Nag, M. A., Junior Assistant, Chemical Department, for his assiduous and ungrudging help in making the nitrogen estimations.CONDITIONS UNDER WHICH THEY ARE FORMED. 339 small quantity of the crystals of nitrite from the last crop was left with the mother liquor and the excess of mercury ; 1 2 days afterwards a single, colourless, bright crystal was observed, and 2 days after this a large crop of the same kind of crystals was collected. This salt, on analysis, was found to be that described below as ‘ I Marignac’s salt.” C. Nit~ic acid (1 : l).-The action was immediate and very energetic, torrents of red fumes being evolved, and the liquid turning bluish to greenish ; after about half an hour, the action seemed almost to cease.At the end of about 20 hours, a crust of long, colourless needles was formed ; the lower part of the crust, however, consisted of the yellow nitrite mixed with the former. D. Nitric acid (1 : 2).-The action was somewhat less energetic, the product consisting practically of yellow salt, a small portion only being transformed into colourless needles. Beliaviour of &t&c Acid towcwds Mewus*ous Nitvite. Strong nitric acid, in the cold, has no immediate action on the salt ; but, after a few minutes, energetic action sets in. I f themixture is heated immediately after adding the strong nitric acid, a violent action begins, copious red fumes are given off, and a clear solution of mercuric salt is obtained.If, after adding strong nitric acid, a small quantity of water is poured in, action a t once commences, nitrous fumes are evolved, and the liquid becomes bluish; a t the same time, a few glo- bules of mercury separate, but disappear on warming the liquid, which contains both mercurous and mercuric salts. If, however, the salt be treated with cold, dilute nitric acid, the action is very slow, bubbles of gas being given off a t intervals ; it is only after the action has con- tinued 3 to 4 days that the salt dissolves, and colourless crystals of mercurous nitrate (“ Marignac’s salt ’7) crystallise out. In$uence of the psesence of Nitvow Acid irz promoting the fwmation of the Nitrite. Russell,* Divers,? and, lately, Veley $ have come to the conclusion that it is the nitrous acid present in the nitric acid that plays the prominent part in the dissolution of metals like silver, mercury, and copper, &c.In order to decide what advantage, if any, would be gained if nitrous acid were initially present, three parallel experiments mere started si m ul t aneousl p. 1.-50 C.C. of colourless nitric acid, sp. gr. 1.410, diluted mith 150 C.C. of water, to which mas added an excess of mercury. * C. S. J., 1874, 27, 3. -t. Ibid., Trans., 1883, 43, 443 ; Trans., 1885, 47, 231. Proc. IZoy. Soc., 1890, 48, p. 458.340 RAY: THE NITRITES OF MERCURY AND THE VARYING 11.-The same as above, with n few drops of red fuming nitric acid. 111.-The same as in I, with 5 C.C. of red fuming nitric acid. In I, after the lapse of about 15 minutes, there was scarcely any depo- sit of yellow needles, in I1 the deposit was distinctly visible, in I11 more so; after the lapse of another hour, a deposit was formed in I; in fact, the amounts in I and I1 were much the same ; whilst in I11 i t was some- what larger. Next day, the yield was found to be practically the same in all three.It is evident, therefore, that nitrous acid over and above that present even in colourless nitric acid, gives a slight advantage at first, but this disappears in the long run. I . Monhydmted Mercurous Nitrite. 11. Bask Mwcuroso-mercuyic ATit&es ; ic?zd 111. Mercuric Nitrite. Mercurous nitrite, Hg,(NO,),, has been shown to undergo partial de- composition when treated with water, thus: Hg,(NO,), = Hg(NO,), + Hg.Nearly 22 per cent. of the salt, however, remains in solution CGS suck. When the solution was hot and concentrated, it was noticed that a yellow, powdery mass separated on cooling, and, on analysis, this was found to be the unaltered nitrite, Hg,(NO,),. On allowing a some- what dilute solution to evaporate spontaneously in a shallow dish, tho salts mentioned above were obtained in succession. A detailed descrip- tion of each is given below. I. Monhydrated Mercurous Nit?-ite : Hg,(NO,), + H,O.-In the course of 2 to 3 days a crop was obtained consisting of glistening, pale, lemon- yellow prisms. The action of water on this salt is precisely similar to that on mercurous nitrite. When kept in contact with water for some time, metallic mercury, in a fine state of division, begins to separate.The method of analysis was the same as that employed for mercurous nitrite. For results, see Table. On comparing the result with that of mercurous nitrite, it would ap- pear that the rate of dissociation of this hydrated salt is differer,t, although in its general behaviour it resembles the former. (Vide B I, 11, 111, Table, p. 345.) That the present salt contains water of crystallisation is proved by the fact that, when kept in the desiccator over strong sulphuric acid, it effloresces somewhat ; but the former salt, Hg2(N0,),, neither loses in weight nor in brilliancy under similar conditions. As the analyses given represent different preparations, it is evident that a salt of constant composition is always formed. Of the several salts described in the present paper, this is the only one which yielded crystals big enough for measurement.Mr. T. H. Holland, of the Geological Survey of India, kindly undertook to exa- mine the crystals (see the next paper).CONDITIONS UNDER WHICH THEY ARE FORMED. 341 11. Bccsic n~ercul.oso-s,iercu~~c iVit&es.- Of these there are two, namely, the a-salt, having the formula 9Hg,0,4Hg0,5N,03,8H,0, and the P-salt, €Ig,0,2Hg0,N,0,,2H20. When the triclinic prisms of the above monhydrated salt had ceased to grow, small, orange- coloured nodules began to appear along with them, and then deep yellow clusters of needles or feathery tufts starting from a nucleus. These two basic salts have been named a and respectively. The analyses (see Table, p. 345) belong to two distinct preparations.The behaviour of the present class of salts was entirely different from that of the previous normal nitrites, When kept in contact with water, scarcely any change was noticed, and no separation of mercnry took place, but on agitating with a few drops of dilute nitric acid, they dissolved completely. Dilute nitric acid, therefore, can be used in the diagnosis of the two classes of salts-normal and basic. If diluto nitric acid is poured on the normal salt and the mixture warmed, copious red fumes are at once evolved and an energetic action begins ; a small portion of mercury separates, dissolving slowly in the acid, with gentle effervescence. Nitric acid, in fact, seems to act in a two-fold manner. First, it displaces the nitrous acid, and then dissolves the mercury set free.Mercurous nitrate, for the most part, with only a small proportion of mercuric nitrate, remain in solution. When the salts are 6asic, nitric acid seems first to enter into combina- tion with the base, and if the acid be very cautiously added drop by drop, not the least trace of nitrous fumes is evolved. Dilute nitric acid does not appear t o exercise any oxidising action on these salts. In analysing these salts, they were dissolved, as explained above, and the mercurous and mercuric mercury estimated as calomel and sulphide respectively. (Vide C I-IV, D 1-111, and E I-IX, Table, p. 345). The water in this and the following salts is easily given off when they are gently heated in a test-tube, but it is not given off in the desiccator, even when they are finely powdered ; it seems preferable, therefore, to regard it as ‘‘ water of constitution ” (vide Marignac’s salt,” below).On referring to the table of results of analyses, it mould appear that the mercurous mercury is sometimes too high by 0.6 to 0.8 per cent., whilst the mercuric mercury is too low on an average by about the same amount. The explanation appears to be that none of these salts could be washed or crystallised, and that, during the process of drying on a porous tile, some portion of the thick mother liquor was absorbed by the salts. 111. Mercwic fiiti-ite, 1 2Hg0,5N20,,24H,O.-After the yellow, feathery crystalline tufts of the /3-salt had ceased t o be deposited, the mother liquor was still found to contain distinct traces of the mercnr- ous salt, and the salt which now began to appear consisted of thin342 RAY: THE NITRITES OF MERCURY AND THE VARYING scales, almost white with a faint yellowish tint ; these were, however, slightly contaminated with the mercurous salt. When the mother liquor had evaporated to dryness,very thin scales were formed, adhering t o the bottom of the basin, and consisting purely of the mercuric salt ; these were eztsily detached from the dry, granular residue, com- posed mainly of mercuric nitrite with a slight admixture of the mer- curous salt. These scales, which were almost white with a yellowish tint, were kept over sulphuric acid before being analysed.The presence of water was proved qualitatively. Trccnsformcction of the Nityite into Nitrate.(a) Monl,yd~i6ted Memuyous Nitmte, Hg,(N0J2 + 2H,O.-The cir- cumstances under which the nitrite is transformed into the nitrate have already been alluded to (see ante, p. 341). At first, I came to the conclusion that the nitrate formed is invariably “ Marignac’s salt,” a description of which will be found below. It has lately been observed, however, that this is not the case. When the nitrite is prepared from an acid diluted in the proportion of 1 : 3, the conversion of this salt into a nitrate takes place more rapidly than when dilute acid 1 : 4 or 1 : 6 has been used. Sometimes in the course of two days, or even one day, colourless, soft crystals make their appearance side by side with the nitrite, but they soon disappear to reappear again in another form; they are highly efflorescent, falling t o powder when exposed t o dry air.I n fact, whenever the transformation of the nitrite into nitrate takes place slowly, the more stable “Marignac’s salt ” is formed, and this explains why this nitrate has been so long overlooked by workers in this field. The new mercurous nitrate is sometimes deposited in isolated crystals, and sometimes as a thick crust ; in the latter case, some of the mother liquor always remains enclosed. Pvep. I.-For analysis, small individual crystals were picked out. 1.0388 of the salt lost, in the desiccator, 0.0660 ; loss = 6.35 per cent. 0.1300 of thisdehydrated salt gave 6.2 C.C. moist nitrogen a t 31“ and Prep. II.-0*4406, keptover H2S0,, lost 0.0275 (loss = 6.24 per cent.), 759 mm. and gave 0.3665 of HgS.Theory for Theory for Found. ......... 76.49 H g 71-43 76.33 - N ........... - 5.34 - 5.13 ........ 6.30 (mean) - H,O 6-43 - ,. HgNO3-I- H&. HgNO,. is hydr. salt. 8s dehydr. s k . (a) Narigmac’s salts 5Hg20,3N,0, + 2H,O or 3Hg2(N0,)2 + 2Hg,(OH), or Hg2(N0,)2,4Hg2(OH)N03.-This is the form into which the normalCONDETlONS UNDER WHICH THEY ARE FORMED. 343 nitrite, described above, is ultimately converted. Regarding this compound, the information in Watts’ Diet ioncc~y of Chemisty, edited by Morley and Muir (vol. iii., p. 514) and in Roscoe and Schor- lemmer’s well-known treatise, is very vague and meagre. The BC- count given of it in Fremy’s Encycl. (tome iii., 14“ Cahier, p. 243), based on Marignac’s original memoirs,” is more complete, but the me- thod of preparation, or rather formation, of this salt is different from that described below ; and this probably explains the want of uniformity in the formulaj proposed by Gerhardt and by Marignac respectively. The formation of the nitrite and its ultimate conversion into the nitrate is fully explained in my first paper (Zoc.cit.). In confirmation of the views there put forward, the following proof may be adduced, The residues from several preparations of the nitrite, consisting of mercury mixed up with some nitrite, together with the mother liquor, were in one case stored up in a tall, well-stoppered bottle, but the vessel did not burst, nor was the stopper thrown out. The fact is, there was no pressure of gas inside; the bubbles of nitric oxide during their ascent through the long column of liquid were completely absorbed.At first, mercurous nitrite gradually formed and accumu- lated, but afterwards slowly dissolved, and in the course of about two months a hard crust of Marignac’s salt ” was deposited on the surface of the mercury, from which large, well-formed crystals with sharp edges projected. I am able fully to confirm Marignac’s statements as to the general properties of this salt, The crystals are very hard, and colourless; retain their lustre unimpaired when exposed to the air, and do not lose water over sulphuric acid in a vacuum ; they give up water, however, easily enough when gently heated in a test-tube. It is necessary to bear in mind that the mercurous nitrite is not directly changed into this nitrate, but passes through the transitional form of the monhydrated nitrate Hg2(N0,), + 2H20, although this latter stage oftentimes appears to be omitted.A m Zysis. I. 0.4152 gave 03945 HgS. Hg=81.88. 111. Ob1877 ,, 6.2 C.C. moist nitrogen at 34” and 755 mm. N = 3.47. Theory requires Hg = 81.96, N = 3.44 per cent. This salt is a definite and stable compound, the analytical results fully confirming Marignac’s formula ; nearly a dozen analyses of different preparations were made. This affords independent testimony from a high authority as to the trustworthiness of the methods of * Ann. Chiwz. Phys., 1849, [3], 27, 515. II. 0’3458 ,, 0.3290 HgS. Hg=82.01.344 RAY: THE NITRITES OF MERCURY, ETC. estimating mercury and nitrogen employed throughout the present investigation.I n a future communication, I hope to throw further light on the formation as well as on the constitution of the nitrites described above. flunammq. From the foregoing investigation, it seems to be established- 1.-That by the action of dilute nitric acid in the cold,* the strength varying from 10 to 23 per cent. or so, mercurous nitrite is cclwccys formed. 2.--That the mercurous nitrite thus formed slowly dissolves in the mother liquor, resulting in the production of mercurous nitrate of two kinds (a), monhydrated mercurous nitrate, Hg,(NO,), + 8H20, and (b), the basic nitrate, termed ‘ I Marignac’s salt.” 3.-That when a neutral dilute solution of mercurous and mercuric nitrites (the products of dissociation) is allowed to evaporate spontsne- ously, monhydrated mercurous nitrite, Hg,(NO,), + H,O, two mercuroso- mercuric nitrites, and a basic memukc nitrite are successively formed.4.-That of these salts only two may be said to contain real ‘‘ water of crystallisation,” namely, those termed monhydrated mercurous nitrite and nitrate respectively, in that they are efflorescent, losing water rapidly in a dry atmosphere ; the rest may be held to contain ‘‘ water of constitution.” CHEMICAL LABORATORY, PEESIDENCY COLLEGE, CALCUTTA, July, 1896. * Some commentary is, perhaps, needed on the expression “in the cold,” used throughout. The average temperature of Calcutta at mid-day may be taken as 32.9” in the summer season, whilst in winter it is nearly 22.2”. These temperatures have been obtained from sixteen years’ observation of the thermograph (dry)-at the local meteorological office.Table of Besults of Analyses.2.485 1586 1'436 0'1,452 05125 1.046 05978 0.8334 0.9331 0.3064 0.669 0 451 0.480 0'500 0'5564 0.2032 0 6330 0'4734 0'4126 0.242 0'331 0'4966 0.5116 0'1288 0*188 - Weight found of Free' Hg. - 3.339 - - )'OSO 3 '1 60 3'6814 0.7685 - - - 0.221 0.203 0.243 0'277 0'310 0'236 - - - - - 0.256 - - HgS. - 0.577 1-36 - 0.194 0.392 0'148 0.1654 I - - 0.210 0.202 0.263 0'3015 0'3975 - - - - - 0.235 0'238 0'1054 Percentage of Free' Hg. 'nus Hg. - 18.18 - - 12'26 14-64 69'35 69'95 - - - 41.62 -10.05) 41 13 43'27 - 41.55 42.33 - - - 42.49 - 31.30 - - 32.62 32'34 15-29 15.28 - - - 40.13 40'26 40'0s 41'04 40'72 I - - - 41.31 40.01 1 Percentage found. '01. of moist nitro- gen 111 c.c. Total 7.9 =32"),(p = 758) mm 7'6 it. 32" and 758 mm. 16-4 it 32" and 760 mm. G.0 I t 32" and 756 mm. 80'94 . (mean) 81-70 78-95 1 (mean) 84.94 . (mean) 81-29 1 (mean) 82.35 - 82-59 83.05 6 '6 I I t 31" and 759 mm. 8.9 it 31" and 758 mm. I 8250 70.54 7 '3 .t315" and751 mm. I - N. 5.69 2.67 2'62 3.14 - 2.91 (mean) I 4'09 - Percentage, theoretical. Totall Hg. - 81-30 78-45 85'77 83'32 70'55 - 4'11 I} Remarks . The "free" Hggenerally comes out too low. (Stse anfe, p. 337.) * Estimated ns total mer- cury. (See p. :W.) The range within which the salt is formed is a wide one ; thus the successive crops D I, 11.111, and E I, 111, IV, VLII, and I X , hare the same composition. The crystallisation was started April 1, and the last crop collected May 6, 1896. t Estimated as total mer- cury. the salt being pre- vioully oxidised by means of HNOa

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346 HOLLAND : CRYSTALLOGRAPHY OF THE XXT;IV.-Crystallog7.cc23hy of the Monhydrated Mercwous Nitrite. By T. H. HOLLAND, A.R.C.S., F.G.S., Deputy-Superintendent, Geological Survey of India. THE crystals supplied me by Dr. R8y are lemon-yellow, and seldom exceed 3 mm. in length. Their small size, delicacy, and tendency to rapid decomposition in the warm, moist atmosphere of this climate, rendered their manipulation for crystallographic measurement a matter of considerable difficulty. As a rule, too, only the faces on one side of the crystal-the free-growing surface--exhibited a suficiently high lustre for work with the reflecting goniometer ; continuous work in one zone, therefore, was possible only to a limited degree. I believe, however, that the results recorded are correct t o within 6' of arc, which will be sufficiently precise for the recognition of similar forms on cryst,als of isomorphous compounds which may be produced in future researches.The crystals belong t o the triclinic system, and generally exhibit only the four forms represented by the eight faces shown in Fig. 1. FIG. 1. The angles between the normals to these faces are as follows :- C.WZ = 59" 41'. ac = 83" 20'. mc=61" 23'. pc=42" 57'. pa=61° 11'. pm'= 96" 33'. From these measurements, c and a will naturally be selected as pinacoids, of which c will conveniently be the basal plane, but the angle between the faces cb and nz is so wide that it seems unadvisable to select m as the other vertical pinacoid. Its relations to cc agree more nearly with the faces generally regarded as prisms ( 03 P), and this arrangement receives additional support from the appearance ofMONHYDRATED MERCUROUS NITRITE.347 faces which appear to be the corresponding prism faces on some very minute crystals which I have examined under the microscope, but FIG. 2. a' ct which are far too small for goniometric work, Fig. 3 is a projection of one of these small crystals on a plane perpendicular to the vertical FIG. 3. crystallographic axis. By comparing it with Fig. 2, which is a similar projection of the commoner type of crystal, and which I have exa- mined goniometrically, it will be seen that the traces of a second prism face are shown as well as the plan of a dome-face in the zone of a. I have carefully examined all the crystals at my disposal in hopes of finding a face which might conveniently be taken as the-other ver- tical pinacoid, b, but, so far, without success, To select the face m for this purpose mould give a most unusually great inclination of the crystallographic axes, and I have, therefore, deferred the calculation of these angles, and consequently of the axial ratios, until further mate- rial may reveal some new combinations. The drawings, therefore, represent the average proportions of the crystals, and the faces repre- sented may provisionally be regarded as- c = basal plane (001).CL = macropinacoid (100). m = prism (iio). p = pyramid (1 11). The angular relations between the normals t o these faces will be sufficient at least for their identification by future workers. Dr. RBy has called my attention to the statementin Fremy's Encg- clopddie Chipmique (vol.iii., 1889, p. 382), according to which silver nitrite crystallises in oblique prisms with an angle of 59"-a result not very different from the angle between the faces a, m in this ccm- pound. But Dr. ROy's analyses indicate the presence in this corn- pound of half a molecule of water. Examination of the crystals under the microscope shows numerous minute liquid inclusions with a zonal arrangement. Determinations of the specific gravity of the compound would, therefore, be of little345 Ra&Y : MERCURY HYPONITRITES. scientific value. The crystals exhibit strong double refraction when examined between crossed Nicols, and macropinacoidal sections show an extinction angle of 33" to the vertical crystallographic axis. It would be interesting, should further researches reveal any isomorphous com- pounds of similar habit, to ascertain the position of the optic axial plane, as the optical constants of compounds, both natural and artificial, appear to be very sensitive t o small changes in chemical composition.

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DOI:10.1039/CT8977100346

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年代:1897

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345 Ra&Y : MERCURY HYPONITRITES. XXXV. -Mer'cur y Hypo nit it es. By P. C. RAY, D.Sc. (Edin.). PRELIMINARY NOTICE. IT has been shown elsewhere* that mercurous nitrite, on prolonged contact with a large bulk of water, partially dissociates into mercury and mercuric nitrite, but that nearly 22 per cent. of the salt dissolves ccs such. We have thus a neutral solution containing both mercurous and mercuric nitrite. It occurred to me' that, if this solution were treated according to the method of Divers,? the discoverer of hyponi- trites, it might be possible to obtain the corresponding mercury compounds. Memm-ozcs Hyponitrite. Divers reduced sodium nitrite by means of sodium amalgam, neutralised the solution with acetic acid, and finally added silver nitrate to it. This method, however, proved to be a failure in the present case.Instead of mercurous hyponitrite, as was expected, there was an almost immediate grey, and even blackish, deposit of metallic mercury. The explanation of the reduction in this case is probably to be looked for in the formation of hydroxylamine simultaneously with the hyponi- trite. It thus became necessary to find a method of preparing sodium hyponitrite to the exclusion of this reducing agent. On consulting the literature on this subject, I came across Zorn's method as improved by Dunstan and Dymond (Trans., 1887, 51, 646). I found that the sodium hyponitrite prepared by their method is quite free from hydroxylamine ; and, although a trace of ferric hydroxide, pro- bably in a colloidal form, passes through the filter paper, imparting to the liquid a slight brown colour, it is completely precipitated and the solution becomes perfectly clear on allowing it to stand overnight.Pmpratiom. -To the solution containing mercurous and mercuric nitrite, sodium hyponitrite solution in a highly diluted form is cautiously added drop by drop ; a copious, flocculent, yellow precipitate * This V O ~ . , p. 340 ; also Zeit. anorg. Chew., 1896, 12, 365. 'f Proc. Iloy. Soc., vo1. xix. (1870-71).RAY : MERCURY HYPONITRITES. 349 is at once obtained, which is apt to turn slightly greenish afterwards. A good deal depends on the may in which the two solutions are mixed ; for instance, if the order be reversed, or if too much of the hyponitrite solution be used a t once, the precipitate turns grey and even black.Although it is possible to remove the whole of the mercurous mercury by the addition of the hyponitrite solution in successive portions, a considerable quantity of mercuric mercury is carried down along with the mercurous. If more hyponitrite is now added to the filtrate con- taining only mercuric nitrite, a voluminous, gelat>inous, white precipitate, exactly resembling aluminium hydrate, is thrown down. There are substantial grounds for believing that the yellow substance obtained above by fractional precipitation is a mixture of mercurous and mercuric hyponitrites. It thus became necessary to study the properties and composition of the latter before those of the former could be ascertained. Mercuric Hyponitrite. The solution containing the mercurous and mercuric nitrites was treated with sodium chloride to get rid of the mercurous mercury, and to the filtrate, which now contained only mercuric nitrite, sodium hypo- nitrite solution was added ; the gelatinous, flocculent precipitate thus produced was thoroughly washed on a filter, and dried over sulphuric acid, The impalpable, dirty white powder thus obtained is only sparingly soluble even in boiling dilute nitric acid, whilst strong nitric acid, strange to say, has scarcely any action on it; it is, however, readily soluble in warm, dilute hydrochloric acid.Two separate preparations were analy sed. I. 0.2558 salt gave 0.2516 HgS. Hg=84.83.* 11. 0.2238 ,, ,, 0.2180 HgS. Hg=83.96. 11. 0.2328 ,, ,, 6.6 C.C. moist nitrogen a t 33Oand 757.5 mm.K = 2.97. The formula Hg(NO), + 3Hg0 + 3H,O, or Hg(NO), + 3Hg(OH), re- quires Hg = 83.16 ; N = 2-91 per cent. The presence of water was proved qualitatively ; it is easily given off when the substance is gently heated in a test-tube. Analyses of two separate preparations of the light yellow powder, a mixture of mercurous and mercuric hyponitrites, gave the following results after being dried over sulphuric acid. I. 0.371 gave 0.367 HgS. Hg=85.28. 11. 0.1565 ,, 0.1532 HgS. Hg=84.37. The nitrogen in I amounted to 4 per cent. Hg,(NO), requires Hg = 86.95 ; N = 6.09 per cent. * As the sodium hyponitrite solution was alkaline, it is very likely traces of mercuric oxide were carried down ; hence the percentage of mercury is rather too high. VOL. LXXI. i 3 E350 DUNSTAK AND CARR: CONTRIBUTIONS TO OUR The low percentage of nitrogen and of niercury in the mixture is now easily accounted for, as it contained a considerable proportion of mercuric hyponitrite.Apart from the resnlts of the analysis, the reasons for believing that in the above inixture me really have R mercurous hyponitrite are (1) That when gently warmed with dilute hydrochloric acid a part of the mercury is thrown do1611 as calomel and bubbles of a gas are slowly given off, con- sisting apparently of a mixture of nitrogen and nitrogen monoxide ; (2) That the pale yellow, amorphous substance resembles in physical properties the analogous silver compound. If the silver compounds be coinpared with the corresponding mercury salts, it is found that the colour is deeper in the case of the metal of high atomic weight ; silver nitrite, for example, is pale yellow, whereas mercurous nitrite is distinctly yellow ; silver bromide is pale yellow, and mercurous bromide has been obtained as yellow spangles ; again, silver iodide is distinctly yellow, and the colour of mercurous iodide is, perhaps, a shade deeper." The hyponitrites of mercury have been found to be far more stable towards heat than the nitrites and nitrates of this metal. I am continuing this work in the hope of discovering a method of obtaining pu!w mercurous hyponitrite, and I also intend to take up a systematic examination of the gases evolved by the action of heat and of dilute acids on these compounds, on the lines of Divers and of Berthelot and Ogier.? CHEMICAL LABORATOET, PRESIDENCY COLLEGE, CALCUTTA.

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350 DUNSTAK AND CARR: CONTRIBUTIONS TO OUR ~XIIiVI.-Co7bt?’ib~tio12~ to ozw Kuozr!ledge of the Aconite Alkaloids. Pcwt X I V.-O.iz Pseudaconitine. By WYNDHAM R. DUNSTAN, %LA., F.R.S., and FRANCIS H. CARR, A.I.C., Salters’ Company’s Research Pellom in the Laboratories of the Scientific Department of the Imperial Institute. 1~ previous papers communicated to this Society, an account has been given of an investigation of the principal properties and decomposition products of the alkaloid aconitine, derived from the roots of Aconitulrn Nci,peZZus. The enquiry has since been extended to a simiIar examination of the alkaloids occurring in other species and varieties of aconite. At * During the preparation of nitroethane by the action of mercurous nitrite on ethylic iodide, I have obtained mercurous iodide in the shape of bright yellow scales.See also Yvon (Cmnpt. rend., 1873, 76, p. 1607). Conipt. rend., 1883, 96, 30.KNOWLEDGE OF THE ACONITE ALKALOIDS. 351 the request of the Government of India, an investigation is being made, in the Scientific Department of the Imperial Institute, of the alkaloidal constituents of the chief kinds of aconite indigenous to India, especially of those which are highly poisonous, or are reputed t o be of medicinal value. I n this connection, Dr. H. A. D. Jowett has described (Part XI11 of this series) the principal properties and decomposition products of ntisine derived from the Aconituna hetevoplyllZuL.l?t of India. I n a previous communication, and in the present paper, we give an account of pseudaconitine, the highly poisonous constituent of the aconite occurring in Nepaul, which is usually regarded as Aconitum fei-ox, and locally known as ‘‘ bish” (bikh). Our previous knowledge of this alkaloid is almost wholly due to the researches of Alder Wright, who, in conjunction with Luff, gave an account of its properties in a paper communicated to this Society in 1878.The material employed in our work consisted of roots of the plant, which were specially collected with great care in the Himalayas under the supervision of Dr. George Watt, the Reporter on Economic Products to the Government of India. I n a preliminary notice communicated to the Society two years ago (Proc., June, lS95), the authors described some of the properties of pseudaconitine. They showed that its hydrolysis occurs in two stages, in the first of which acetic acid and a crystalline base verntrylpseud- aconine are formed, and in the second the elimination of a molecule of dimethylprotocatechuic acid takes place with the formation of pseud- aconine.It has also been shown that, when pseudaconitine is heated in the dry state, one molecular proportion of acetic acid distils over, and a base is left, to which the name pyropseudaconitine was given. This base, when hydrolysed, furnishes dimethylprotocatechuic (veratric) acid and pyropseudaconine. The present paper gives a more detailed account of the experiments which furnished these results, and also an account of other observations on the properties of the salts and derivatives of pseudaconit ine. Extvccction of the AZkdoiJ.-Several methods have been tried for the extraction of the base froin the root, involving the use of methylic, ethylic, and amylic alcohols.Finally, a mixture of methylic and amylic alcohols, in the proportion of 5 to 1, was adopted as the most efficient solvent. The metbylic alcohol is distilled from the slightly warmed percolate, under reduced pressure, when a quantity of a t separates; this removed, and the alkaloid is extracted from the amylic alcohol by making it with very dilute (1 per cent.) aqueous hydrochloric acid. The solution is then shaken with ether, to remove E l 3 9352 DUNSTAN AND CARP,: CONTRIBUTIONS TO OUR the dissolved amylic alcohol, the alkaloid liberated by the addition of dilute ammonia, and then extracted by shaking with ether in the usual manner.On evaporating the dried ethereal solution, white crystals separate, which are recrystallised by dissolving them in dry chloroform, adding dry ether, and then dry light petroleum, until a slight turbidity is produced; by this means, a considerable supply of pure pseudaconitine was obtained. Judging from the yield obtained from the roots of Aconitum feyoz, it would appear that more pseudaconitine is present in them than there is of aconitine in the roots of A . Nctpellus; but this is a question to which we shall return in a future paper. Propes.ties of Pseudc6conitine.-The pure base crystallises well. Mr. W. J. Pope has kindly examined some fairly well-defined crystals, with the following results. '' The crystals of pseudaconitine consist of small, colourless, trans- parent crystals of rhomboidal shape, having a rather vitreous lustre. Owing to the poor character of the images obtained from the various faces, the measurements given below are of no great accuracy; they would indicate that the crystals belong to the orthorhombic system.That the crystals are, however, not orthorhombic, is shown by the faces which they exhibit, and also by the interference figure observed in polarised light. Considering, for the purpose of description, that the crys- tals are really orthorhombic, the following faces are always observed : -(010), (OlO), (lll), (111), ( l i l ) , (IiT), (ili), and ( n l ) , with traces of the form (110) ; the two faces (111) and (711) are never observed. This observation was made on all the crystals examined-ten in number, belonging to two different crops-and the same faces of the forms (010) and (111) were found in every case ; this arrangement of faces is not possible in the hemihedral subdivisions of either the orthorhombic or monosymmetric system.The crystals must, there- fore, be assigned to the rare anorthic hemihedral system, two of the forms having the indices 111 being present as half-forms only, and the interaxial angles a, p, and y being equal to 90" within the rather wide limits of error incurred in the measurement of crystals such as those now described. "The crystals present the appearance shown in Fig, 1, and have the axial ratios-KNOWLEDGE OF THE ACONITE ALKALOIDS. 353 n : b : c = 0.8362 : 1 : 0.6938. FIG.1. '' The following angular measurements were obtained : No. of .Angle. measnrernen ts. ho = 010 : 111 23 61" 09 = 11_1 : 111 10 54 bo = Ol_O :211 9 117 00 = 11; : 111 18 67 00 = 111 : 111 7 111 00 = 111 :Ti: s 94 00 = 111 : 111 4 S5 pp = 110 : 110 4 fS p p =: 110 : i i o 1 Linii ts. 14'-- 62" 17' 27 - 56 46 26 -118 19 1 2 - 68 59 1 4 -111 35 1 -- 95 29 2 - 85 37 54 - SO 16 - IIean. 61" 51' 56 5 117 5s 68 34 111 24 94 35 55 20 79 20 101 4 Calculated. - 56" 12' 118 6 111 26 94 29 E5 31 I 9 4s 100 1 2 - "The crystals are very brittle, and possess a good cleavage; the latter however, could not be determined. On examining a cleavage fragment under n very wide angle objective, one optic axis is seen t o emerge a t the edge of the field; it shows that the dispersion is inclined, which is only possible in the monosymmetric or anorthic system.The hemi- hedral character of the crystals is of interest, because non-superposable hemihedrisiu is so rarely observed on crystals of the natural alkaloids, that it has been said not to occur. (Wyrouboff, Ann. C?&12. P?~ys., 1894, [vii], 1, 11). "The crystalline form of aconitine has been determined by Tutton (Trans., 1S91, 59, ZCS), who found the crystals t o be orthorhombic, but did not observe hemihedrism. Although morphotropic relationships would seem t o exist between the crystalline forms of aconitine and pseudaconitine, yet these can hardly be worked out from the data now- given for the latter alkaloid ; the following corresponding angles on the two compounds seem t o show some similarity." Aconitine.Pseudaconitinc. 100 : 121 60" 39' 010 : 111 61' 54' 010 : 121 57 42 100 : 111 55 43 001 : 121 46 33 001 : 111 47 15" The crystals melt with decomposition at 201", acetic acid gradually distilling off; the melting point is fairly sharp if the substance is put into the bath heated to 150" and the temperature slowly raised. Wright and Luff (Zoc. cit.) have recorded 104-105" as the melting point of354 DUXSTAN AND C'ARR: CONTRIBUTIONS TO OUR pseudaconitine. They state that Ohe alkaloid contains 1 H,O, which is lost at loo", but we have not been able to confirm this observation. Pseudaconitine dissolves readily in alcohol, chloroform, and acetone, less readily in ether, very slightly in water, and scarcely a t all in light petroleum. A determination of the specific totatory power, using an alcoholic solution, gave Pseudaconitine is dextrorotatory.c = 1.12 I = 2 d??E. a = 25' t = 15" 100 x 25 whence [aID=5i 1.12 + 18" 36'. The ordinary salts of pseudaconitine are Isvorotatory, and usually Combustion of the alkaloid made with soluble in water and alcohol. the material dried at 100" gave the following results. I. 0.2612 gave 0.5964 GO, and 0,1694 H,O. C = 62-99 ; H= 7.20. 11. 0.2587 ,, 0.5975 CO, ), 0.1484 H,O. C=62*96 ; H=6.37. These figures nearly correspond with those calculated from the for- mula proposed by Wright and Luff (Trans., 1878, ii, 151)) namely, C1,GH,,NO,,, for which the calculated percentages are, for carbon, 62.88 ; for hydrogen, 7.13. Like aconitine, pseudaconitine and its salts, even in very dilute solution, give rise to a persistent tingling and numbing sensation on the tongue, and are highly poisonous.From preliminary experiments on the relative toxicity of various aconite alkaloids, which have been made at our suggestion by Dr. F. W. Tunnicliff e, it mould appear that pseudaconitine is slightly more toxic than aconitine. S d t s of Pseucln conitine. Pseudnconitine / ~ y d ~ o c h h i d e , (&H4,'N0,,,HC1.-\~e have not suc- ceeded in obtaining this salt in a crystalline condition. It has been prepared by the direct action of dilute hydrochloric acid on both aqueous and alcoholic solutions of the base, but all attempts t o crystallise it from water, alcohol, or a mixture of alcohol and ether have resulted in the production of a colourless varnish.Pseudaconitine Iqch-obromicle, C1,,H,,NO1,,HBr.-This salt is pre- pared by dissolving the base in dilute hydrobromic acid and evapo- rating the solution. A colourless varnish remains, and on adding n, little alcohol to this, the mass rapidly becomes crystalline. It is best purified by dissolving it in dry alcohol and adding dry ether until a slight turbidity is produced; it then separates in large, cubical crystals often arranged in rosettes. The salt readily dissolves in alcohol and water, but is insoluble in ether and light petroleum. The crystals con tain 2H,O, which are expelled on drying at 100-103". The driedKNOWLEDGE OF THE ACONITE ALKALOIDS. 365 substance melts a t 191". by heating a t 100-103" in an air bath. 0.546 lost 0.0863 = 4.8 per cent. H,O.Determinations of the bromine in the undried and in the dried The water of crystallisation was estimated substance gave the following figures. 0.3379 nndried salt gave 0 0751 AgBr. 05197 dried salt gave 0.1227' AgBr. C36H4nNOl,,HBr + 8H,O requires H,O = 4.5. Br = 9.95 per cent. C,,H,,NO,,,HBr requires Br = 10.3 per cent. of the specific rotatory power led to the folloming result Br = 9.44. Br = 10.05. An aqueous solution of the salt is lzevorotatory ; the determination I = 2 cln8 c = 0.6635, Pseudaconitine, therefore, resembles aconitine in being a dextro- rotatory base whose salts are laevorotatory. Pseudccconitiqze hydriodide, C:36H4SN012,HI.--This salt is precipi- tated in an amorphous condition when aqueous potassium iodide is added to an aqueous solution of pseudaconitine hydrobromide.Although at first amorphous, the precipitate rapidly becomes crystalline ; it may readily be purified by recrystallisation from a mixture of alcohol and ether. Psezcdacovaiti?ze qzitrccte, C,GH,nNO,z,HNO,.-This salt was prepared by Wright and Luff (Zoc. cit.) by dissolving the base in dilute nitric acid and precipitating the nitrate by adding strong nitric acid, in which it is only sparingly soluble; this method, however, is not to be recom- mended, as strong nitric acid is very apt to decompose the alkaloid. By dissolving the alkaloid in dilute nitric acid to exact neutrality, and evaporating to dryness, the nitrate is obtained as an amorphous varnish, which crystallises a t once on the addition of alcohol ; it is readily puri- fied by crystallisation from a mixture of alcohol and ether, and when pure may be crystallised from water.The dried salt melts at 192" and effervesces at a slightly higher temperature ; the melting point is fairly sharp if the substance is put into the bath at 155" and slowly heated. The water of crystallisation was determined by heating the powdered, air-dried salt a t 100-105". 0.1975 lost 0.014 H,O. H,O= 7.0 per cent. C:3GH,,NOl,,HNOs + 3H,O requires H,O = 6.7 per cent. 5 C.C. of a solution saturated at this temperature yielded, on evaporation, 0.209 gram of salt. 100 C.C. of water at 15", therefore, dissolves 4-15 grams of salt. Its solubility in water a t 15" was determined.356 DUNSTAN AND CARR: CONTRIBUTIONS TO OUR Hydrolysis of Pseuduconiiiine.We have previously pointed out (Zoc. c i t . ) that, in addition to the pseudaconine and veratric acid, observed by Wright and Luff, acetic acid is formed by the hydrolysis of pseudaconitine, and we have also shown that the hydrolysis may occur in two stages. To determine the first stage only in the hydrolysis, namely, the elimination of acetic acid with the formation of veratrylpseudaconine, it is best to employ a process similar to that which was found to answer in the case of aconitine. A neutral aqueous solution of a pseudaconitine salt, pre- ferably the sulphate, is heated in a sealed tube at 135" for 3 hours, the amount of acetic acid formed is determined by direct titration with N/10 alkali, and the alkaloid, after being liberated by the addition of sodium carbonate, is dissolved by shaking with ether.A solution containing 0.168 gram of alkaloid (as salt), after this treatment, required for neutralisation 4.3 C.C. of N/10 alkali = 7.5 per cent. of acetic acid, which is slightly lower than that calculated for one molecular proportion, namely, 8.7 per cent. Analysis of the silver salt of this acid showed that it contained 64.56 per cent. of silver. Silver acetate contains 64.66 per cent. The formation of veratrylpseudaconine may thus be represented by the following equations. C3,H,9N0,, + H,O = C3,H,~NOll + CH,*COOH. Psendaconitine Veratrylpseudaconine Ye,.c~t,ylpseudcLconine. The pure base crystallises from ether i n large, irregular crystals, which are nearly insoluble in water and in light petroleum, but readily soluble in ether, alcohol, and chloroform. They melt at 199" when put into the bath at 150".Ade- termination of the specific rotatory power in alcoholic solution led to the following results. A solution of the base is lzvorotatory. t = 16', U = - 1'16' c = 1.5035 Yeratrylpseudaconine, therefore, unlike its analogue benznconine, exhibits rotatory power of the opposite sign t o that of its parent base. Aconitine and benzaconine are both dextrorotatory, whilst pseud- aconitine is dextrorotatory and veratrylpseudaconine lzevorotatory. Combustions of the base, dried at 100-103", futnished the following results, showing it to be a monhydrate. I. Carbon 61.44; hydrogen 7.15 per cent, 11. ,, 61-01 ; ? ¶ 7-05 99 9 , Calculated for C,,H,7NOll,H,0 : Carbon 61 -54 j hydrogen 7.34 per cent.KKOWLEDGE O F THE ACONITE ALKALOIDS.357 This alkaloid and its salts have a very bitter taste, but produce no tingling sensation, and do not appear to be poisonous. Ve1wat?.yl~seudc~conine Hyds.obronaide, C,4H,7NO11,HBr.-This salt separates from a mixture of alcohol and ether in large, prismatic crystals which contain 3H20. 0.3478 salt lost 0.0264 H,O a t 100'. 0.3478 ,, gave 0.0842 AgBr. Br = 11.21. C,,H,~NO,,,HBr + 3H20 requires H,O = 6.95 ; Br = 11.02 per cent. The salt is soluble in water, alcohol, and chloroform. Ve~~c~~~~~Zpseudaconi.ne nitmte, C,4H,7N0,1,HN03, crystallises from a mixture of alcohol and ether in rhombic prisms arranged in rosettes. In melting, two fairly sharp points may be noticed, one at 222", when softening and change commences, and at 2 3 2 O , when the salt melts sharply with decomposition.Combustion of the anhydrous salt gave C = 57.34 ; H= 6-40 per cent. : C,,H,7N0,1,HN03 requires C = 57.62 ; H = 6.77 per cent. Vercctil:?/1psezcdccconine aus.ichZoride, C,4H,~NOl,,HAuC14, is thrown down as a pale yellow, amorphous precipitate when auric chloride is added to a solution of the hydrochloride. It is insolubTe in water, ether, and light petroleum, but readily soluble in ethylic and methylic alcohols, chloroform, and acetone ; it could not be crystallised from any of the last-mentioned solvents alone, or on the addition of ariy of the former to them. Pseudaconine. H,O= 7.5. The second stage of the hydrolysis by which veratrylpseudaconine passes into veratric acid and pseudaconine, may be best effected by adding alcoholic soda to an alcoholic solution of pseudaconitine, or veratrylpseudaconine.Hydrolysis takes place rapidly, and is complete in about 2 hours. Dilute sulphuric acid is then added, the filtrate evaporated, the veratric acid extracted from the acidified solution by ether, and the pseudaconine by chloroform, after rendering the solution alkaline with ammonia. 0.2143 gram of alkaloid gave 0.0556 gram of veratric acid = 25.94 per cent, The acid melts a t 178' and exhibits the other properties of di-methyl- protocatechuic acid (veratric acid). This stage of the hydrolysis may therefore, be represented by the equation, Calculated for one molecular proportion, 26.49 per cent. C,H,7N0,, + H20 = G,H3(OCH3),*COOH + C,,H,,NO, Veratryl pseudaconine Veratric acid Pseudaconine.Pseudaconine is an amorphous, hygroscopic base readily soluble in water, chloroform, alcohol, and acetone, and less readily in ether. Its aqueous solution is strongly alkaline to litmus. All attempts to crgstallise the base uncombined with its solvent have been unsuccessful. VOL. LXXI. c c3.58 DUNSTAN AND CARR: CONTRIBUTIONS TO OUR An aqueous solution of pseudaconine is dextrorotatory. The specific rotatory power of an aqueous solution was determined with the follow- ing results. a[20°] = +32.5 ~ = 0 . 8 9 6 Z=2 dfih, 100 0.541 = +300 6'. whence [a], = __-- ~ 2 x 0.896 Yseudaconins hyd~ochlos*ide, C,,H,,NO,,HCl, wagprepared by dissolving the base in dilute hydrochloric acid to neutrality. Many attempts made t o crgstallise this salt from various solvents were unsuccessful, although, on one occasion, crystals were obtained from an alcoholic solution which had stood for six months ; these were prisms and melted at 68'.Pseudccconilze hydvobromide, C,,H,,NOs,HBr, was prepared in the same manner as the hydrochloride, but it could not be crystallised. Pseudaconine nitrrwte, C,,H,,NO,,HNO,, was prepared by the direct action of dilute nitric acid on the base, and also by double decomposi- tion between silver nitrate and the hydrochloride, and barium nitrate and the sulphate. It was always obtained in an amorphous state. Pseudaconine sulphccte, ( C,,H,,NO,),,H,SO,, was prepared by acting on pseudaconine with dilute sulphuric acid, but this salt could not be crystallised.Pseudaconine c~uu?*ichlo~icEe, C,,H,,NO,,HAuCl,, is precipitated when auric chloride is added to a concentrated solution of pseudaconine hydrochloride. It is a yellow, amorphous precipitate sparingly soluble in water, and could not be crystallised from any of its solutions. When light petroleum is used, the yellow colour of the solution is clis- charged and it becomes colourless, although no gold is precipitated. This change, in other cases, has been observed t o be due to the produc- tion of an aurichlor-derivative by loss of hydrogen chloride from the aurichloride. We have so far failed to crystallise an aurichlorpseud- aconine from this solution. Pyropseudccconitine. As previously recorded by us, when pseudaconitine is heated slightly above its melting point, it effervesces and loses acetic acid.A deter- mination of the amount of acetic acid which distils under these circumstances, proved that one molecular proportion of acetic acid is expelled ; analysis of the silver salt of the acid proved it to be silver acetate. The reaction may therefore be represented by the following equation. C,,H,,NO,, = ~,H,O, + %4H,,NO,, Pseudaconitine Pyropseudaconitine Yyropseudaconitine, an anhydride of veratrylpseudaconine, is obtained from the residue by solution in dilute acid, and is purified by fractional precipitation from this solution with dilute ammonia. The colourlessKKOWLEDGE OF THE ACONITE ALKALOIDS, 359 fractions are dissolved in dilute acid, precipitatecl with ammonia, and the pure base extracted from the alkaline solution by ether.The base so far has only been obtained as an amorphous varnish, nearly insoluble in water, but readily soluble in alcohol, chloroform, and ether. I t s salts appear to crystallise well; they have a bitter taste, but produce no tingling, and do not seem to be poisonous. The hydi-iodide crystallises in prisms. Although, in publishing our preliminary notice of psendaconitine we stated that we were engaged in a complete investigation of the alkaloid, this did not prevent Herr lllartin Freund from examining the alkaloid, and, nine months after the appearance of our paper in the Proceedings of this Society, publishing in the “Berichte ” (Bey., 29, 6,552) a n account of his and Herr Niederhoffheim’s experiments on the subject. They adopt Wright’s formula for the alkaloid, and confirm our conclusion that pseudaconitine, like aconitine, contains an acetyl group. For the rest, they record melting points which differ somewhat from those pre- viously recorded by us, but since these points are in most cases decom- posing points, and depend on the conditions under which the observations are made, no real importance attaches to these discrepancies. As to their assertion that pseudaconine is the anhydride of the aconine derived from aconitine, it is t o be observed that this statement is based solely on the numerical coincidence that the formuIa for pseud- aconine deduced from Wright’s formula for pseudaconitine, namely, C,5H39N08, differs by one molecule of water from the formula which Freund has suggested €or aconine (C,,H,,NO,). But, as we have else- where pointed out, Freund’s new formulze for aconitine and its deriva- tives cannot at present be accepted as proved, and we have so far seen no reason to depart from a formula for aconitine, differing very slightly from that originally suggested by Wright, which does not allow of pseudaconine ( C,,H3,N08) being regarded as the anhydride of aconine (C2,H3,N0,,). As a matter of fact, we have already described an anhydride of aconine (pymconine), whose properties are very different from those of pseudaconine. We have pleasure in acknowledging the skilful help afforded us in the early stages of this work, in tlie Research Laboratory of the Phar- maceutical Society, by Mr. H. T. Durant. SCIENTIFIC DEPARTJIEST, IIVlPERIzlL INSTITUTE, LOXDON. c c 2

ISSN:0368-1645    

DOI:10.1039/CT8977100350

出版商:RSC    

年代:1897

数据来源: RSC

摘要:

360 THORPE AXD RODGER: );SYVII.-Tlze Viscosity of iWixtwes of &Iiscible Liquids. By THOS. EDWr-aRD THORPE, LL.D., F.R.S., and JAS. \ J T ~ ~ ~ ~ ~ RODGER, xssoc. E.C.S. TT rarely happens that the properties of a mixture of liquids are identical with those which the mixture should possess on the assump- tion that each constituent exercises an influence proportional to its amount. The volumetric a i d thermal changes accompanying the admixture of certain liquids not known to exert chemical action on each other, can only be explained on the supposition that there are forces of attraction between the molecules in the mixture which disturb the equilibriuni previously existing. It may be that the effect of solution in such cases is to break down, to a greater or less extent, the complex molecular aggregates of which certain liquids appear, especially from surface-energy and viscosity observations, to be com- posed ; solution under these circumstances has much the same effect as heat, I n other cases, it may lead to the formation of aggregates of the same or of dissimilar molecules. Aggregates of the latter kind would not necessarily be chemical compounds in the ordinary sense, any more than those of the former kind.Still, it must be confessed, the differences between such physical aggregates and chemical compounds are rather of degree than of kind. Poiseuille (Menz. de Z’lnst. de Pc~s’is, 1546, 9, 433) was one of the earliest to attempt to use the property of viscosity as a measure of the play of internal forces between heterogeneous molecules in a liquid in the special case of mixtures of ethyl alcohol and water. He concluded that the maximum time of flow was shown by the mix- ture which manifested the maximum degree of contraction, and that both phenomena were connected with the formation of the hydrate C,HG0,3H,0.The same conclusion was arrived a t by Graham (Phil. Tyans., 1861, 373) who found that similar, although, as a rule, less pre- cise, relationships might be detected in mixtures of water with the ordinary mineral acids--nitric, sulphuric, and h ydrochloric-or with certain fatty acids-formic, acetic, butyric, and valeric. The work hitherto published is insufficient, both in extent and pre- cision, to admit of a final judgment. It must be admitted that Graham’s contention, that definite hydrates of these alcohols and acids may be recognised by viscosity observations, is not wholly established, The work of Noack on mixtures of ethyl alcohol and water, and that of Wijkander on mixtures of acetic acid and water, would seem to indicate that the phenomena of maximum contraction and maximum viscosity, if not independent, are a t least not directly related to theTHE VISCOSITY OF MIXTURES OF MISCIBLE LIQUIDS.361 existence of definite hydrates in the liquids. (c.$ Sprung, A m . Ph~s. CJmn., 1876,159, 1; Traube, Ber., 1886,19, 871 ; Arrhenius, P.X.? 1889, [v], 28, 3 9 ; D'Arcy, P.M., 1889, [Y], 28, 221.) A significant fact connected with the instances of the kind here referred to, is that they are all cases of the admixture of liquids containing molecular aggregates, but in what manner this circumstance is associated with the maxima of contraction and viscosity remains t o be shown.Wij kander (Lzcnds. Phys. Sccllsk. Jzcbel.skrift, 1878) has also measured the viscosity at various temperatures of mixtures of aniline and benzene, ether and chloroform, ether and carbon disulphide, ether and alcohol, and benzene and alcohol. Our knowledge of this paper is derived from the abstract in Beibl, 1879, 3, 8, from which it would appear that in no case was the viscosity identical with that calculated by the admixture rule; in general, the observed viscosity was less than the calculated value. I n the case of mixtures of ether with chloroform, and of ether with carbon disulphide, there were inflexion-points in the curves ; but no simple relation between the viscosity co-efficients of a mixture and those of its constituents could be deduced.C. E. Linebarger (Amer. J. Sci., 1896, [ivJ, 11, 331) has recently published a number of observations, made at the uniform tempera- ture of 25", on mixtures of pairs of chemically indifferent and miscible liquids, which in the main corroborate Wijkander's results. The observed viscosities in general are less than those calculated by the mixture-rule, except, possibly, in the case of mixtures of benzene ancl chloroform, and mixtures of carbon disulphide with benzene, toluene, ether, and acetic ether, where possibly the temperature of observation (25.) mas too near the boiling point of the carbon disulphide to make any specific influence which that liquid might exert a t lower temperatures perceptible.As a rule, the greater the difference between the viscosities of the pure liquids, the greater was the difference between the calcnlatecl and the observed values of the mixtures. I n previous communications (Phil. T~aizs., 1894, 185, 9. 379 ; Phil. TTC~?~ZS., 1897, 189, A. 71) we have given the results of the measurement of the viscosity of a considerable number of pure liquids a t various temperatures between 0' (except when the substances were solid a t that temperature) and their ordinary boiling points. I n the present paper, we communicate the results of some observations made with the view of throwing further light on the relation of the viscosity of a, mixture of two chemically indifferent and miscible liquids to the viscosity of its constituents.A sufficiently exact and sufficiently extensive study of this question would afford answers to many questions of interest. For example, it would enable us to say whether the viscosity was related to the number of molecules per unit-volume or per unit-surface, ancl hence it would throw light upon the question of how viscosity362 THORPE AND RODGER: observations, and indeed all observations which depend on surface effect, should be treated. It mould also enable us to determine whether, in the case of a mixture of a simple and a complex liquid, the values of the viscosity gave any indication of the decomposition of molecular aggregates, and how such decomposition was related t o dilution and temperature; whether, in fact, the effect of adding a chemically indifferent liquid to a complex one mas the same as raising the temperature. For such purposes, it would no doubt be generally convenient to select mutually soluble and chemically indifferent liquids of approximately the same boiling point, but of densities and viscosities its widely different as possible. Our previous work enables us to form a considerable number of pairs of such liquids, On the present occasion, we desire to communicate the results 01)- tained from observations of several series of mixtures of carbon tetra- chloride and benzene, methyl iodide and carbon disulphide, and ether and chloroform, the last pair of which we studied on account of the yelatively considerable evolution of heat which accompanies the admix- t,ure of these liquids.The method of observation mas the same as that previously employed, and the apparatus was identical with that described in our firstpaper (PluiZ. YTU~S., 1894, 185, p. 410, et Seq.). A .--Ccci.bon Tet ruth Zoride und Benzene. The carbon tetrachloride used in making the mixtures was obtained by repeated fractionation from a large quantity of the commercially pure liquid which had been well washed with potash solution, and dried over phosphoric oxide. It boiled constantly a t 76-62' (corr.) The benzene was free from thioplien. After digestion with sodium wire, it boiled constantly at 79-98" (corr.) and froze at 5.53". Three mixtures of these liquids were made, having respectively the following percentage composition : Carbon tetrachloridc.Benzene. RIixture I... ............ TT.63 22.37 ,, I1 ............... 56.31 43.79 ,) 111 ............... 32.30 67-71 The densities of the pure liquids and of the mixtures a t Oo/Oo were- Carbon t et rach lori d e ........................ 1 % 3 2 0 Mixture I .............................. 1,3816 ,, II .............................. 1-2042 ,, I11 .............................. 1.0530 Benzene ................................. 0.9001 Their densities a t higher temperatures are calculated from their thermal expansions, as determined by the dilatometric method describedTHE VISCOSITY OF MIXTURES OF MISCIBLE LIQUIDS. 363 by one of us in 1893 (Trans., 63, 262). The following table shows the relative volumes of the mixtures at intervals of 10".The values for carbon tetrachloride are those found by one of us in 1880 (Trans., 37, 200) ; those for benzene are the mean of the concordant observa- tions of Kopp, Luginin, and Adrienz. Temp. O0 10 20 30 40 50 60 70 Carbon tetra- chloride. 10000 121 245 372 502 637 778 924 Mixt. I. 10000 121 245 373 503 638 778 924 Mixt. 11. 10000 121 2 45 372 505 640 779 923 Mixt. 111. 10000 119 243 368 500 635 774 919 Benzene. 10000 118 240 364 495 6 30 770 916 It is evident that inno case does the volume of a mixture differ very much from the value calculated by the admixture rule from the volumes of the constituents a t the same temperature. The following table shows the densities at Oo, 20°, 40", and 60" of the mixtures, calculated from the densities a t 0", and the volumes a t the respective temperatures, as given above.These are compared with the values of the densities of the mixtures, calculated from the known densities and thermal ex- pansions of carbon tetrachloride and benzene, on the assumption that no change in volume occurs on admixture. Temp. Mixt. I. Mixt. 11. Mixt. 111. oo Obs. 1-3816 1.2042 1.0530 Calc. 1.3809 1,2035 1.0525 2oo Obs. 1.3486 1.1754 1.0280 Calc. 1.3481 1.1750 1.0278 4oo Obs. 1,3154 1,1463 1.0029 Calc. 1.3151 1.1464 1.0027 6oo Obs. 1.2819 1.1172 0.9774 Calc. 1.2815 1.1171 0.9771 The observations would appear to show that a very slight contraction occurs on mixing carbon tetrachloride and benzene, as already found by F. D. Brown (Trans., 1881, 39, 207), who concluded that the maximum contraction occurred in the case of a mixture containing about 40 per cent.of the tetrachloride. The following table shows the values of the viscosities of the various mixtures a t different temperatures :364 THORPE AND RODGER: Mixture 1. Temp. 7. 0.66" 0.01 184 10.59 0.00990 21-26 0.00833 31.41 0.00719 41-32 0*00630 51.62 0.00555 62-38 0.00491 Mixture 11. Temp. 7. 0*41° 0.01080 10.24 0-00905 20.58 0.00770 30.79 0.00663 40.85 0.00577 52.30 0.00499 64-05 0.00437 73.33 0.00398 Mixture 111. Temp. 1. 0.55" 0.00984 10.06 0.00831 21-10 0.00696 31.70 0.00598 39-93 0.00536 52.0'7 0.00468 63.15 0.00407 73.6 1 0.00365 The following table shows the visccsity of the several mixtures at intervals of 10" between 0" and 70", taken from the curves representing the foregoing observations : Temp.O0 10 20 30 40 50 60 70 Mixt. I. 0*01196 0~01000 0.00850 0,00734 0.00641 0,00566 0*00503 Mixt. 11. 0.01088 0 -0 0 9 08 0.00776 0.00671 0.00583 O-OO513 0-00456 0.0041 1 Mixt. 111. 0;00994 0-00832 0.00707 0.00612 0.00536 0.00473 0.00422 0-00379 The following table gives, for 0" and for 60°, the observed value of the viscosity in the case of the three mixtures, and the values calculated on the assumption that, if the mixture contains na grams of liquid n and n grams of liquid b, the viscosity of the mixture is (@% + n%)/(m + n). Temp. Mixt. I. Mixt. 11. Mixt. 111. Obs. 0.01196 0.01088 0 -009 9 4 O0 Calc. 0.01247 0.01 152 0.01046 Obs. 0.00503 0.00456 0,00422 ' O 0 Calc. 0-00540 0.00499 0.00453 It will be seen that at both temperatures the observed values are less than the calculated values by about 6 per cent.The admixture rule, therefore, does not apply. Linebarger (Zoc. cit.) has measured the viscosity of three mixtures of carbon tetrachloride and benzene a t the temperature of 25", and, although our results confirm his conclusion that the actual viscosities of such mixtures are lower than those calculated from the admixture rule, the values obtained by us differ to some extent from those given in his memoir. On plotting our numbers showing the relation betweenTHE VISCOSITY OF MIXTURES OF MISCIBLE LIQUIDS. 365 viscosity and composition a t the different temperatures, we find, for mixtures of the composition of those made use of by Linebarger, the following viscosity values, which, it will be seen, are uniformly higher than those obtained by him.C,H@ CCI,. Linebarger. T. and R. 13-73 86.27 0.00808 0.00821 40.78 59-28 0.00706 0.00739 58.60 41.40 0*00660 0*00680 The difference is mainly due to the circumstance that the viscosity coefficient for carbon tetrachloride at 25" found by Linebarger is notably less than that indicated by our observations. Thus, for carbon tetrachloride at 25", we found 0.00901 ; Linebarger, 0.00883. For benzene at 25', we found 0.005998 ; Linebarger, 0.00599. The foregoing results, expressed in terms of the composition of the mixtures as abscissse and viscositycoefficients as ordinates, are graphi- cally represented in Fig. 1 (p. 366). The straight dotted lines shorn the calculated viscosity values, as given by the mixture-rule. It will be seen that the actual viscosities of the mixtures are uni- formly lower than those calculated on the supposition that each con- stituent exerts an influence proportional to its amount.The greatest difference from the calculated value occurs in a solution containing from 35 to 40 per cent. of benzene, or, in other words, in a mixture of about equal molecules of the two constituents. At Oo, the maximum difference between the observed and calculated values is equivalent to a rise of temperature of about 3.7'; a t 60", the maximum difference is equivalent to a rise of 6.6". I n other respects, there is not'hing ab- normal in the course of the curves. We may assume that, if a mixture has been formed from y C.C. of liquid r6 and q C.C. of liquid b, the time of flow of the volume of the mixture produced will be the sum of the times of flow of p C.C.of liquid CL and p C.C. of liquid b. On this assumption, if m grams of liquid a, having a density pa be mixed with 'rz grams of liquid 6, having a density pb to form m + n grams of a mixture having a density pm, then As this rule would, in all probability, be most, closely obeyed by a mixture produced without contraction or expansion, the case before us affords a good means of testing its validity, since, as already shown, carbon tetrachloride and benzene mix with very little alteration in volume. The results obtained a t O', loo, 20°, 40" and 60' are given in the following table :THORPE AND RODGER: FIG. 1. -COEFFICIENTS OF VISCOSITY. d k t i c r c s of Benzene and Curbon Tetrachloride.Dynes per Xq. Centim. 0 10 20 30 40 50 60 70 80 90 100 Percentage of C,H,.THE VJSCOSITY OF MIXTURES OF MISCIBLE LIQUIDS. 367 Mixture 0" 10" 20" 40" 60" I Obs. 0.01196 0.01000 0.00850 0-00641 0.00503 Calc. 0.01195 0*01005 0.00860 0.00654 0.00517 Obs. 0*01058 0*00908 0*00776 0.00683 0.00456 'I Calc. 0*0108'i 0.00914 o.00782 0-00594 0.00470 Obs. 0 *00994 0.00832 0*00707 0.00536 0.00422 'I1 Calc. 0.00995 0.00837 0°00716 0.00543 0.00431 It will be seen that there is a close agreement between the observed and calculated values a t the lower temperatures, but that, as the tem- perature increases, the difference becomes slightly larger ; that is, the mixtures are less viscous than they should be if calculated from the re- lative amount of their constituents.This may be connected with differences of molecular complexity due to the solution of the benzene. We hare already stated (Zoc. cit., p. 561) that the curve showing the re- lation of the viscosity of benzene to temperature is, as compared with those of its homologues, toluene, ethylbenzene and para- and meta-xylenes, altogether abnormal. At 0", benzene has actually a greater viscosity than any of these hydrocarbons, and it is only at the respective boiling points that the viscosity-constants follow the order of the gaseous molecular weights. B.--iWethyZ Iodide ccncl Cadon DisuZp?Lide. The methyl iodide used was made from pure methyl alcohol. About a litre of t,he product was shaken with mercury, allowed to stand for a couple of days over phosphoric oxide, and distilled.It boiled constantly a t 42.44' (corr.). The carbon disulphide was rectified, placed over anhydrous copper sulphate for a week, decanted, shaken with pow- dered potassium permanganate, filtered, and thereafter shaken with mercury. It was then mixed with an equal volume of olive oil, and after standing for a day, was distilled from a water bath and placed over phosphoric oxide for a meek. It boiled constantly at 46.27" Five mixtures of the two liquids were made of the following per- centage composition : Mixt. I. Mixt. 11. Mixt. 111. Mixt. IV. Mixt. V. Methyl iodide ......... 78.40 61.19 51.89 31-19 17.61 Carbon disulphide ...... 21.60 38.81 48.11 68.81 82.39 (corr.). The densities of the pure liquids and of the mixtures at Oo/Oo were found to be- CH,I. Mixt.I. Mixt. 11. Mixt. 111. Rlixt. IT. Mixt. V. CS,. 2.3335 1.9848 1.7720 1,6782 1.4982 1.3994 1.292368 THORPE AND RODGER: The thermal expansions of three of the mixtures were found to be as follows : Temp. CHJ. Nixt. I. Mixt. 111. Mixt. V. CS,. 0' 10000 10000 10'300 10000 10000 10 11s 120 122 116 116 20 243 244 244 236 236 30 372 373 370 358 360 40 505 506 500 485 489 Dobriner's value for methyl iodide (AizntcZen, 1888, 243, 30) and the values for carbon disulphide published by one of us in 1880 (Eoc. cit.) are introduced for the sake of comparison. The numbers show that the volumes of the mixtures differ but little from those of the pure liquids at the corresponding temperatures, and that in the case of the Mixtures I1 and IV the volume may be taken without sensible error in the reduction of the viscosity observations as intermediate between those c;f I and 111, and 111 and V respectively.The following table gives the comparison, a t O', 20°, and 40°, of t h e densities, deduced by means of the preceding data, with those calculated on the assumption that no change in volume occurs on admixture : Temp. Mixt. I. 3lixt. 11. Nist. 111. Mixt. 1V. Xlixt. V. oo Obs, 1.9842 1.7720 1.6782 1.4982 1.3994 Calc. 1.9878 1.7780 1.6821 1.5017 1.4030 Obs. 1.9369 1.7298 1.6382 1.4631 1.3671 Ualc. 1.9411 1.7365 1-6428 1,4669 1:3705 20O Obs. 1.8886 1.6871 1.5983 1.4279 1.3347 400 Cals. 1.8938 1.693'3 1.6021 1.4318 1.3378 It will be seen in this case that the calculated values are uniformly greater than those actually observed, or, in other words, expansion occurs on mixing methyl iodide and carbon disulphide. The following table contains the mean values of the viscosity co- efficients of the mixtures : Mixt.I. X x t . Temp. rl Temp. 10.02 0.004727 8.87 20.85 0.004303 17.74 30.01 0.003994 25.70 39.01 0.003723 33.48 39.30 0.38O 0*005164 0 ~ 4 1 ~ 11. Jtixt. 111. 7 Teiii y. ?1 0*004807 0.34' 0.004680 0.004475 9.66 0.004357 0.004171 21.57 0.003984 0.003926 30.56 0.003739 0.00371 4 39.38 0.0035 12 0.00355 9THE VISCOSITY OF MIXTURES OF MISCIBLE LIQUIDS. 360 Mist. IV. DIixt. T:. Temp. 17 Temp. 17 0.42O 0.004478 0.50' 0.004358 10.02 0.004131 9.90 0*004037 19.911 0.003825 19.47 0.003752 30.00 0.003566 29-09 0.003494 39.97 0.003341 38.47 0.003268 The values at intervals of loo, as read from the curves obtained by plotting these numbers, are given below : Temp.Mixt. I. Mist. 11. DIixt. 111. Mist. IV. Mixt. V. 0" 0.00518 0.00482 0,00469 0'00449 0.00438 10 0.00473 0 '00443 0 *00435 0-00413 0'00403 20 0'00433 0'00410 0 -00403 0.00382 0'00373 30 0 '00399 0.00350 0 -00374 0 '0 0 35 7 0.00347 40 0.00369 0'00354 0-00350 0 '0 033 4 0 *00323 The values a t Oo and 40°, calculated by the ordinary admixture rule, are given in the following table. Temp. Mist. I. bIixt. 11. Mixt. 111. Mixt. IV. Mixt. V. Obs. 0*00518 0.00482 0.00469 0.00449 0.00438 '" Calc. 0.00558 0.00530 0.00515 0.00480 0.00458 Obs. 0.00369 0.00354 0.00350 0.00334 0.00323 Calc. 0.00389 0.00374 0.00365 0.00347 0.00334 40° It will be observed in this case, as in that of the mixture of carbon tetrachloride and benzene, that the admixture rule does not apply; the viscosity-coefficient s are uniformly lower than the calculated values, the differences between the observed and calculated values becoming less as the t'emperature increases.These results are graphically repre- sented in Fig. 2 (p. 370). The maximum difference between the observed and calculated values occurs in a mixture containing about 40 per cent. of carbon disulphide, that is, in a mixture of about equal molecular proportions of the two liquids. The maximum variation between the observed and calculated values at Do is equivalent to a rise of about 10' in temperature ; a t 40°, the difference is equivalent to a rise of about 7'. I n the following table is given, for temperatures of Oo, ZOO, and 40°, the comparison of the observed viscosities with the values caicu- lated on the assumption that the time of flow of a given volume of a pure liquid is retained when that volume of it is present in a mixture.Temp. Mixt. I. Mixt. 11. Mixt. 111. Mixt. IV. Mixt. V. Obs. 0.005 18 0.00482 0.00469 0.00449 0-00438 O0 Calc. 0.00538 0*00504 0.00489 0.00461 0.00445370 THORPE AND RODGER: Temp. Mixt. I. Xixt. 11. Mixt. 111. Mixt. 1V. Xixt. V. 203 Obs. 0,00433 0.00410 0*00403 0.00382 0.00373 Calc. 0.00446 0.00421 O.OC411 0.00389 0.00379 Obs. 0.00369 0.00354 0.00350 0,00334 0.00323 400 Calc. 0*00378 0.00359 0.00351 0.00336 0.00327 The observed viscosity-coefficients are uuiforrnly lower than the calculated values, although the differences become less and less as the FIG.2. -COEFFICIENTS O F VISCOSITY. Mixtzcres of Methyl Iodide and Car6on Disztlphicle. Dynes per Sq. Ceibtim. 0 10 20 30 40 50 60 70 80 30 100 Percentage of CS,. temperature is raised-exactly the opposite to that which obtains in the case of a mixture of carbon tetrachloride and benzene. This cir- cumstance is probably connected with the slight expansion which O C C I ~ ~ S on mixing methyl iodide and carbon disulphide. C. -Et It el* and C?b I wt-o f orm. About a lifre of ' pure ' ether was shaken with a strong solution of acid sodium sulphite, decanted, mixed with 10 per cent. potash solution, separated, washed with water, and treated three times in succession with dehydrated calcium chloride. After repeated treatment with phosphoric oxide, i t boiled betweenTHE VISCOSITY OF MIXTURES OF MISCIBLE LIQUIDS.3'71 34-83" and 34.89". Corr. and reduced b. p., 34-57', The number given in our previous paper is 34.48'. After standing over phosphoric oxide for a fortnight, it was found t o distil completely between 61.46" and 61.63'. Bar., 770.5 mm. The corr. and reduced b. p. = 61.34". Four mixtures of these liquids were employed. They had the following percentage composition : Bar,, 767.9 mm. For the chloroform, we are indebted to Mr. David Howard. Nixt. I. Mixt. 11. Mixt, 111. Mixt. IV. Chloroform.. . . . . 84.06 59.86 40.20 30.70 Ether ............ 15.94 40.14 59.80 79.30 The densities of the pure liquids and of the mixtures a t O", and the values calculated by the admixture rule, are given in the following table : CHC1,.Rlixt. I. Mixt. II. Mixt. 111. Mist. IV. C',H,,,O. Obs. 1,5255 1.3136 1*0801 0.9389 0.8292 0,7362 Calc. 1.3029 1.0666 0.9295 0.82415 The comparison shows that a notable contraction occurs when ether and chloroform are mixed. The observed densities are found t o lie on n smooth curve showing no inflexion-points. There is, as already pointed out by Bussy and Buignet, a considerable rise of temperature on mixing ether and chloroform. Since the experiments with the other liquids showed that where the difference between the coefficients of thermal expansion of the con- stituents is small, the coefficients of the mixtures may be calculated with sufficient accuracy by the admixture rule, it was deemed unneces- sary for so small a range of temperature to make observations on the thermal expansion of the mixtures. The mean values of the viscosity-coefficients of the several mistnree, ~ L S observed, are given in the following table : Mixtnre I.Mixture IT. 0.43' 0.006744 0.36" 0.005590 9-38 0.005995 9.33 0.004934 20.60 0.005243 19.66 0*004318 29.93 0.004724 39.35 0*003848 Temp. rl Temp. 9 Mixtura 111. Temp. ?1 0.45" 0.004371 9-83 0.003894 19-86 0.003463 29-77 0*003106 3 1-47 0*003060 Mixture I V. 0.45' 0.003483 11.71 0 -00 3 0 6 9 20.64 0.002 79 6 28.92 0.0025 72 Temp. 9372 THORPE AND RODGER: The last observation in the case of Mixture I11 was made 70 minutes after the one previously taken. obtained a t 31-47" lies on the curve obtained by plotting the other- observations proves that the composition of the mixture suffers no sensible alteration on standing even for more than an hour a t the highest temperature a t which measurements were made.The values of r) a t Oo, loo, 20°, and 30°, read from the curves obtained on plotting t.he above numbers, are given below. The fact that the value of Temp. Mixt. I. Mixt. 11. Mixt. 111. Mixt. IV. 0" 0.00678 0.005 62 0*00440 0.00350 10 0.00595 0.00489 0.00388 0.00312 20 0.00528 0 *O 0 4 30 0.00346 0.00281 30 0.00472 0.00382 0.00310 0-00254 The values a t 0' and a t 30°, compared with those calculated by the admixture rule, are given in the following table. Temp. Mixt. I. Mixt. 11. Mixt. 111. Mixt. IV. oo Obs. 0.00678 0.00562 0*00440 0.00350 Calc. 0.00634 0.00535 0.00454 0.00373 3oo Obs. 0.00472 0*00382 0*@0310 0.00254 Calc. 0.00463 0.00391 0.00332 0.00274 These results are graphically represented in Fig.3, where the abscissz of the curves are the percentage amounts of ether in the mix- tures, and the ordinates the viscosity-coefficients at the corresponding temperatures. The dotted lines show the calculated viscosity-values, as given by the admixture rule. It will be seen that there are points of inflexion in €he curves of the observed values, as already found by Wij kander. Wijkander's actual values, however, are not strictly comparable with ours on account of the character of the ether he employed. His viscosity-coefficients for that liquid are about 10 per cent. higher than ours, which were deduced from two independent and closely concordant series of observations made on two different preparations of ether (Phil.Tmns., 1894, p. 518). That the differ- ences are not due to the method of observation is shown by the fact that Wijkander's and our values for chloroform, benzene, and carbon disulphide are in very good accord. Ether is one of the most mobile of liquids, and the correction for kinetic energy may in its case become of considerable importance. Wij kander's higher values may be partly caused by imperfect correction for kinetic energy, or by the presence of small quantities of ethyl alcohol in the sample employed. A s alcohol a t 0' is more than 6 times as viscous as ether, a relatively small amount of alcohol has a marked effect upon the viscosity of the ether.THE VTSCOSlTY O F MIXTURES O F MISCIBLE LIQUIDS. 3’73 The course of the curves is altogether different from that shown by the other mixtures studied by us. Instead of being uniformly lower than the calculated value, the observed value starts by being higher, but, as the amount of ether increases, the variation from the calculated FIG.3. -COEFFICIENTS OF VISCOSITY. Mixtures of Chloroform aitd Ether. Dyiics per Sq. Centinz. Percentage of Ethcr. amount becomes less and less until a t a certain point, depending on the temperature, the two values become identical, after which the actual viscosity becomes less than the calculated value, the general course of the curve resembling that of the other mixtures studied. It is VOL. LXXI, D D374 THORPE AND RODGER : THE VISCOSITY OF MIXTURES, ETC. evident from the curves that as 35O, the boiling-point of ether under ordinary conditions, is approached, the mixture mould resemble other mixtures in having a viscosity uniformly lower than the calculated value, or, in other words, the condition which determines the peculiar behaviour of the mixture is destroyed a t about that temperature.I n t,he following table are given for the temperatures O", lo", 20", and 30" the observed values of q, and those calculated on the assump- tion that a given volume of a liquid when mixed with another liquid maintains the same time of flow as when unmixed. Te m 1'. Mixt. I. hIixt. 11. oo Obs. 0.00678 0.00562 Calc. 0.00589 0.00466 Obs. 0.00595 0.00489 loo Calc. 0.00527 0.00417 Obs. 0.00528 0.00430 20" Calc. 0.00474 0.003'76 Obs. 0.00472 0.00382 300 Calc. 0.00430 0.00341 The actual viscosity is uniformly greater Mixt.111. Mixt. IV. 0.00440 0*00350 0.00393 0.00336 0.00388 0.00312 0.00352 0*00301 0.00346 0.00281 0.0031 S 0.00273 0*00310 0.00254 0*00288 0.00247 than the value calculated on the above assumption, although the differences tend to become less as the temperature rises, or as the quantity of ether increases, The observations described in this paper afford additional evidence of the fact indicated by Wijkander, and supported by Linebarger, that the viscosity of a mixture of miscible and chemically indifferent liquids is rarely, if ever, under all conditions, a linear function of the composition. It seldom happens that a liquid in a mixture pre- serves the particular viscosity it possesses in the unmixed condition. To judge from the instances hitherto studied, the viscosity of the mix- ture is, as a rule, uniformly lower than the mixture rule would indicate, but no simple relation can yet be traced between the viscosity of a mixture and that of its constituents. I n the case of a mixture of ether and chloroform, where there is considerable contraction, and therefore considerable development of heat, on mixing, the viscosity a t low temperatures is greater than the admix- ture rule would indicate, but as the temperature is raised, or asthemixture giving the maximum contraction is diluted, the viscosity eventually ')ecornes less than the calculated value, when the general course of the curve resembles that of such mixtures as carbon tetrachloride and ben- zene, or of methyl iodide and carbon disulphide. The behaviour of a mixture of ether and chloroform would seem, to begin ivith, to beFENTON: A NEW SYNTHESIS IN THE SUGAR GROUP. 375 analogous to that of a mixtureof ethyl alcohol and water, but the con- dition which determines the contraction and the maximum viscosity, whether it be a feeble chemical combination or a molecular aggregation of a purely physical character, is destroyed by heat or dilution.

ISSN:0368-1645    

DOI:10.1039/CT8977100360

出版商:RSC    

年代:1897

数据来源: RSC

摘要:

FENTON: A NEW SYNTHESIS IN THE SUGAR GROUP. 375 XXXVI1I.-A New Synthesis '1'7~ the Sugar Group. By HENRY J. HORSTMAN FENTON, MA. AN account has been given in several previous communications of the for- mation, properties, transformations, aud constitution of dih?/droxymccZeic m i d . (Trans., 1894, a, 899 ; 1895, 67, 48 and 774; 1896, 69, 546) It was shown that the crystals of the hydrated acid, C4H40, + 2H,O are quite permanent in the air at the ordinary temperature, and that the dry acid may be heated to 100" in an inert atmosphere without change. The aqueous solution is, however, very unstable, the acid being split up, sbwly a t ordinary temperatures, and very rapidly when heated to about 60", into glycollic aldehyde and carbon dioxide. The decom- position takes place almost quantitatively, according to the following equation : C4H40, = C,H40, + 2C0,.Glycollic aldehyde can in this way be easily prepared in quantity. On evaporating the solution in a vacuum desiccator, and subsequently removing a small quantity of acid (probably glyoxylic acid), which is produced a t the same time, the aldehyde is obtained as a thick, almost colourless, syrup. It obstinately retains traces of the alcoholic or ether used to purify it, but after long standing in a vacuum desiccator, it can be obtained nearly pure. It has a sweet taste, is somewhat volatile with steam or alcohol vapour, and is easily soluble in water or absolute alcohol, but nearly insoluble in ether. Its aqueous solution quickly reduces Fehling's solution in the cold, and gives, in the cold, a silver ' mirror ' with ammoniacal silver nitrate.It immediately answers Schiff's aldehyde reaction. On oxidation, it yields glycollic acid, and with phenylhydrazine acetate a t 40", it yields the osazone of glyoxal, $JH:N,H*C,H,. CH:N,H*C,H, When this aldehyde is heated for two or three hours in a vacuum a t about 1 OO", it undergoes a remarkable change, becoming transformed into a solid, transyarent.gum which is somewhat brittle when cut with a knife. It is now almost insoluble in cold absolute alcohol, and its aqueous solution only very slowly and imperfectly answers Schiff's magenta reaction for aldehydes. It has a sweet taste, and reduces Fehling's solution slowly in the cold, and immediately on heating ; with ammoniacal silver nitrate, it gives a silver ' mirror.' D U 2376 FENTON: A NEW SYNTHESIS IN TlIE SUGAR GROUP.Analysis and molecular weight determination by Raoult's method, indicate that this substance has the formula C,H,,O, (loc. cit., 67 Exccmincction of the Condensdon Pyoduct . 774) Colour 8eccctions.-The substance answers most, or all, of the well- known cotour reactions for ' sugars,' and the results are, as a rule, more strongly marked than with dextrose under similar conditions. For example, pic& acid, made alkaline with soda, gives a deep red colour on heating ; dipheylai?zine and alcoholic hydrogen chloride give, on heating, a brownish-violet colour ; resowinol and alcoholic hydrogen chloride, and aqueous pyrogallol and hydrogen chloride, both give a ruby-red colour ; phZo?*ogZucinoZ and hydrogen chloride give, on heating a reddish colour changing to a black precipitate. Test for Opticity.-A solution containing 6.4 grams of the substance in 100 C.C.was carefully examined in a Soleil's saccharimeter, and was found t o be entirely inccctive. Formation of Fui~ui.cilcle?~yde.-A 5 per cent. aqueous solution of the substance was heated in a sealed tube at 140" for 4 hours ; a consider- ah10 quantity of brown ' humic ' substance sepnmted, and the liquid, after filtration, was distilled. The clear, colourless distillate, when tested with aniline acetate, gave the intense rose-red coloration characteristic of furf ural. Phenylhydrazine acetate also gave a white precipitate. Another portion of the original liquid was shaken with chloroform, which, after being allowed t o evaporate spontaneously t o a small bulk, was treated with an alcoholic solution of aniline and a drop of hydro- chloric acid; the characteristic rose colour was in this case again produced.Formose, mannose, and a-acrose yield furfursl in a similar way, (Loew, Be?*., 1888,21, 3039; Fischer, Be?*., lS90, 23, 99 and 369). Expeyiments with Yeast.-Three flasks, of about 50 C.C. capacity, were each fitted with a series of bulbs containing baryta water, so that the progress of the changes could be observed. Forty C.C. of water was placed in each flask, and in the first, 1.5 grams of the substance was dis- solved; in the second, a like quantity of dextrose, and the third was left blank for comparison. One gram of well washed brewer's yeast was added t o each, and the solutions were made just perceptibly acid with a drop or two of dilute solution of citric acid.The three pieces of apparatus were placed side by side, and kept at a temperature of about 25". The solution of dextrose showed signs of active fermenta- tion after a few hours, whereas the other two solutions behaved exactly alike, giving no appreciable quantity of carbon dioxide, even after standing for 3 days.FENTON: A NEW SYNTHESIS IN T H E SUGAR GROUP. 37'1 Action of Phenylhydm&e on the ' Xuga~*.'* When EL dilute aqueous solution of the ' sugar ' is mixed with excess of phenylhydrazine acetate, the mixture soon begins to cloud on standing in the cold ; and when heated on a water bath, a bulky, yellow precipitate separates, which increases in quantity and darkens in colour on further heating.With a weak (1-2 per cent.) solution, the precipitate is mostly cryst>alline in appearance, but with stronger solutions, the greater part separates as a deep brownish-red oil which solidifies on cooling ; after washing with water and drying on a porous plate, the precipitate dissolves easily in alcohol or ethylic acetate, and partly in cold benzene or ether. Heated for one or two hours with about 300 times its weight of water, a considerable portion of it dissolves, anii is precipitated from the solution on cooling in bulky, lemon-yellow flocks resembling sulphide of arsenic in appearance. Under the microscope, this precipitate is seen to consist of fine yellow needles. sug,zr ' was dissolved in about 50-70 times its weight of water, and mixed with phenylliydrazine dissolved in 50 per cent.acetic acid in the proportion of 1 part of 'sugar,' 2 parts of phenylhydrazine, and 2 parts of glacial acetic acid. The yield of crude, air-dried osazone obtained was generally about equal to, or slightly greater than, the weight of ' sugar ' taken. About 6-8 grams of the ' sugar ' were employed for each experiment, and the mixture was generally heated on a water bath at 90-100" for about 5 hours. Experiment I.-Glycollic aldehyde was heated in a vacuum for about 2 hours on a water bath at 90-loo", the product being subsequently converted into osazone in the manner described above. The crude osazone was well washed, drained with the aid of the pump, then boiled with about 300 times its weight of water for Ig-2 hours, and filtered while hot.The lemon-yellow precipitate which separated on cooling was twice recrpstallised from hot water in the same way, dried in a vacuum, recrystallised from hot benzene, and dried at 80". The melting point of this specimen was 164-1 65O. I n the following experiments, the I. 0.1324 gave 0.3071 CO, and 0.0679 H,O. C = 63-25 ; H = 5.69. XI. 0.1168 ,, 0.2706 CO, and 0.0631 H,O. C=63*18; H=5*90. ,, 26.5 C.C. nitrogen a t 19"and 758.8 mm. N = 18.13. These numbers do not a t all agree with those required for a normal They me between those calculated for tetrosazone and 111. 0.1711 hexosazone. pentosazone, as will be seen in the following table. glycollic aldehyde in a vacuum will be referred to as the ' sugar.' * For want of a more appropriate term, the gummy product obtained by heating378 FENTON: A NEW SYNTHESIS IN THE SUGAR GROUP.Calculated for C. H. N. Diosazone, C,,H,,N, . . , . . . . , . . , . 70.58 5*S8 23.53 Tetrosazone, ClGH18N,0,. . . . . . . , . . . . 6.04 18.79 Pentosazone,C17H,oN,0, . , . . , . . . . . . . 6.09 17-07 Hexosazone, C18H,,N,0,. . , . . . . . . . . . 6.15 15.64 64.43 62-19 60.33 It seemed probable, therefore, that the condensation of the glycollic aldehyde had been incomplete, and that the osazone produced was a mixture of hexosnzone with an osazone of lower molecular weight. Experiments were therefore made to ascertain whether a different result would be obtained by heating the glycollic aldehyde for longer periods, or at higher temperatures.Expeviment 11.--The aldehyde was heated at 90-100° for about 10 hours. The osazone was prepared as before, and was purified by re- crystallisation three times from boiling water, and then from 50 per cent. alcohol. It was dried a t loo', and melted at 160-161'. I. 0.1179 gave 0,2737 CO, and 0.0650 H,O. C = 63.31 ; H = 6.12. 11. 0.1815 ,, 1s-3 C.C. nitrogen at 16' and 758 mm. N- 17-99. Expeyiment 1II.-The aldehyde was heated at 95-100" for 1 hour, and then further heated at 106-10So for 4 hours more; the osazone was purified in the same manner as in Experiment 11. It melted at 157". 0.1258 gave 0.2934 CO, and 0.0684 H,O. The residue which was left after the purification of this specimen was again boiled with about 3 litres of water. The insolublepart was then heated with 50 per cent.alcohol, the solution allowed to evaporate, and the residue recrystallised from 50 per cent. alcohol. It had a darker colour than the other specimens, and ,melted a t 151-1552'; its composition was, however, the same. C = 63.60 ; H = 6.04. 0.1112 gave 0.2134 CO, and 0.0650 H,O. C = 63.62 ; H=6.16. It is evident), therefore, that varying the time and temperature within the above limits had little, if any, effect on the composition of the osazone produced, Loew (Bey., 1888, 21,275), on analysis of the osazone of formose (from formaldehyde), obta.ined the numbers C = 63-65, H = 6.81. (The nitrogen value was not given.) Prom this, he at first assumed that the osazone had the composition C,,H,,N,03, being formed from the sugar in the following way.C,H120, + BN,H,C,H, = U,,H,,N,O, + 3H,O. Afterwards, Fischer showed that crude formosazone was a mixture of several substances, and, by exhaustive fractional separation with various solvents, he was able to isolate, at any rate, two normal hexo-FENTON: A NEW SYNTHESIS IN THE SUGAR GROUP. 379 sazones having the formula C,,H,,N,O,, p-ncrosazone o r formosazone, m. p. 144", anda-aerosazone, m. p. 216--217°. (Fischer, Bey., 1888,21, 988. Fischer and Passmore, Ber., 1889, 22, 359). Since there is such a close similarity between the numbers obtained by Loew for crude formosazone and those resulting from the several analyses given above, it was considered advisable to attempt a separa- tion of the crude substance by the method which Fischer employed in the case of crude formosazone, the details of his method being followed as closely as possible.Expes.inzent IF.-The glycollic aldehyde was heated, as in the last experiment, for about 5 hours a t 100-106°; 8'2 grams of the sugar ' thus obtained were dissolved in 250 C.C. of water, mixed with phenyl- hydrazine acetate in the same proportions as before, and the mixture heated on a water bath for 14 hours. Most of the osazone separated as a dark-reddish oil which solidified on cooling, the remainder appearing as a reddish-golden, crystalline precipitate ; the product was washed with water, drained, and air-dried on a porous plate fop 2 days. About 9.5 grams of crude osazone were obtained. It was then twice ground in a mortar with a little cold benzene, drained and washed on a filter with cold benzene, and after again drying in the air it wasground up with about 80 C.C.of anhydrous ether in successive portions. The ether solution, on evaporation, gave a yellow residue which was partly soluble in boiling water, but the quantity of purified product thus obtained was small, and was not therefore examined. The residue left undissolved after treatment with ether was heated with the smallest possible quantity of ethylic acetate, in which practi- cally all was dissolved; nothing separated from this solution after standing for 3 days. (In the case of formosazone, a sparingly soluble portion separates on standing.) The solution was then evaporated on a water bath, and the residue (about 3.6 grams) heated with a litre of water for 14 hours, and filtered; the filtrate, on cooling, deposited a bulky, yellow precipitate, which under the microscope was seen t o con- sist of aggregates of yellow needles. This product, after drying in a vacuum, melted a t 141-142", and gave the following result on analysis.0.1145 gave 0.2603 CO, and 0,0621 H,O. The residue (about 2 grams), after extraction with water as above, was again heated with about a litre of water for 3 hours, repeatedly washed with boiling water, and then twice recrystallised from hot 50 per cent. alcohol, and vacuum dried. This specimen was darker in colour than the part soluble in water ; it melted a t 134-136O. C = 63.41 ; H = 8.09. C=62*00; H=6*02. 0.1131 gave 0.2630 CO, and 0.0620 H,O. These results show undoubtedly that the original omzone is a mix-380 FENTON: A NEW SYNTHESIS IN THE SUGAR GROUP.ture, but that the process of separation is not sufficient for the isolation of its constituents. Pu@ication of the C n d e ‘ Sugcw.’ Experiments were now made with a view of separating the hexose from unaltered glycollic aldehyde (or other ‘ sugar ’ having a lower molecular weight than hexose), assuming, as was probable from the analyses above recorded, that the condensation to hexose had not been complete. It was previously shown that the crude ‘sugar ’ is nearly insoluble in absolute alcohol, whereas glycollic aldehyde dissolves easily, so that the latter, a t any rate, should be capable of removal in this way. As, however, mere treatment with cold alcohol did not promise to be of much service owing to the gummy nature of the substance, it was heated to boiling with about three or four times its weight of absolute alcohol.After boiling and stirring for a few minutes, the whole dis- solved, forming a clear solution which, on cooling, turned milky ; after standing for some hours, a considerable portion separated as a soft gum which became harder after washing with alcohol. (If, however, the quantity of alcohol used to dissolve the sugar be insufficient, the substance does not separate on cooling, although it is immediately precipitated in flocks on adding cold alcohol.) The separated portion, after being treated first with a little warm alcohol, and then rubbed repeatedly with fresh portions of cold alcohol, was similar in appear- ance to the original crude ‘ sugar,’ and behaved in a similar way with Fehling’s solution, stc.With phenylhydrazine, however, a different r e s d t was obtained, as will be described below. The alcoholic solution which was poured off from the separated gum, when allowed to evaporate in a desiccator, leaves a reddish-yellow, thick syrup, which tastes sweet and has the odour of treacle. If this be again heated for a few hours in a vacuum, a further yield of solid gum is obtained apparently identical with the original sugar. It was not used in these experiments, however, since its identity, although very probable, had not been established. Action of Pli,enp?lydraxine on the PuyiJed Pq*oduct.-The osazone was prepared in the same manner as before, and was purified by first rubbing with small quantities of cold benzene or ether, and then crys- tallising from boiling water.The yield of crude osazone was somewhat smaller than in the previous cases, but it mas lighter in colour and less contaminated with resinous matter, and the yield of purified pro- duct was, apparently, larger in proportion. C = 60.17; H=6*26. 11. 0.11 37 ,, 0.2525 CO, and 0.0658 H,O. C = 60.56 ; H = 6.43. I. 0.1120 gave 0.2471 CO, and 0.0632 H,O. 111. 0.1354 ,, 18.2 C.C. nitrogen at 14’ and 749 mm. N = 15.80.FENTON: A NEW SYNTHESIS IN THE SUGAR GROUP. 381 A normal hexosazone, as stated above, requires C = 60.33 ; H = 6.1 5 ; N = 15.64 per cent. The specimen analysed in I mas prepared from a different sample of the sugar from that analysed in I1 and 111. The first was purified by treating it with ether, and then crystallising from hot water; the second by treatment with benzene, crystallisation frdm hot water, and then from 50 per cent.alcohol. The melting point of the second specimen was determined; i t darkened a t about 150°, and melted a t 168-170°. Action of Heat o n the Ptwijecl P?*odzict.-The crude ' sugar ' is but slightly changed by further heating for several hours at about 100'. A specimen, for example, which had been heated in a vacuum t o 90-100' for about 10 hours gave the foliowing result on analysis. C = 40.34 ; H = 656. Both specimens were vacuum dried. 0.1293 gave 0.1913 CO, and 0.0766 H,O. Another specimen, similarly heated for about 12 hours. 0.1286 gave 0.1920 CO, and 0.0773 H,O. C = 40.71 ; H = 6.67.C,H,,O, requires C = 40.00 ; H = 6.66 per cent. The product which has been purified by alcohol, however, after heating in a vacuum to S0-106", shows more evident signs of dehy- dration. I is a specimen which had been heated for 2 hours a t SO-100' ; 11, another specimen which had been heated for 4 hours a t 100-106°; 111, the same specimen as analysed in I1 but heated again for 6 hours at 100-106° (that is, 10 hours altogether); IV was another specimen similarly heated for 24 hours. I. 0.1157 gave 0.1776 CO, and 0.0691 H,O. C=41*86; H=6-63. 11. 0.1174 ,, 0.1807 CO, arid 0.0686 H,O. C = 41.97; H = 6.49. 111. 0.1792 ,, 0.2848 CO, and 0.0985 H,O. C = 43.34 ; H = 6-10, IV. 0.1323 ,, 0.2119 CO, and 0.0724 H,O. C = 43.68 ; H= 6.0s. It appears, therefore, that the substance, after 2 to 4 hours' heating, has the composition represented by C,,H,,O,,, which requires C = 42.10 ; H = 6.43 per cent.After this, the loss of water takes place more slowly, and, when heated for 24 hours, the composition approximates to C,H,,O,, which requires C = 44.44 ; H = 6-17 per cent. This behaviour, on heating, is very similar to that of formose (Wehmer and Tollens, Annuben, 1888, 243, 336; Loem, Ber., 1888, 21, 3039), and the product much resembles Butlerow's ' methylenitan ' in proper- ties. It is transparent, bnt darker in colour than the original sugar, and is harder and more brittle, so that it may be powdered. I n taste, and odour when heated, it somewhat resembles caramel.382 FENTON : A NEW SYN‘L’HESIS I N THE SUGAR GltOUI’. Sunzmccry of Resccl ts.Glycollic aldehyde, when heated a t about 100” for a few hours in a vacuum, undergoes condensation, and produces a solid, transparent gum. The substance so produced has a sweet taste, reduces Fehling’s solntion, and gives various colour reactions characteristic of ‘ sugars.’ Heated with water a t 140°, it yields fnrfural. With phenylhydrazine, an osazone is produced which is to a considerable extent soluble in boiling water, and crystallises in yellow needles. It is optically inactive, and appears to be incapable of undergoing fermentation by yeast. Analysis of this condensation product, and molecular weight cleter- minations by Raoult’s methocl, indicate the formula C,H1,O,. An exhaustive study, however, of the osazone, produced under varying conditions, shows that the condensation is never perfect, the hexose being mixed with a ‘ sugar ’ of lower molecular weight, probably un- altered glycollic aldehyde or possibly tetrose.By treatment with boiling alcohol, however, this lower compound may be removed, and the purified product then gives, with phenylhydrazine, a normal hexosa- zone, C,,H,,N,O,, melting a t 16S-1’iOo. When this purified product is heated in a vacuum a t 100-106° for 2 t o 4 hours, i t has the formula C,,H,,O,,. On further heating, water is lost more slowly, and, after 24 hours’ heating, the composition approximates to C,H,,O,. The dehydrated product is darker in colour than the original ‘ sugar,’ and is harder and more brittle, so that it is capable of being powdered. Several other interesting experiments, of course, suggest themselves in connection with the ‘ sugar’ ; for example, the effects of oxidation by nitric acid and by bromine, whether levulinic acid is produced by the action of hydrogen chloride, and whether the purified ‘ sugar ’ is capable of resolution into isomeric modifications.The scarcity of material, however, owing to the expense of manufacture, compels me to reserve these experiments for a future communication. The fact that a ‘sugar’ can be produced in this simple manner from tartaric acid may possibly help to throm light, in certain cases, upon the natural formation of carbohydrates. The changes may be briefly ex- pressed as follows. (1) C,H,O, - H, = C,H,O,. (2) C,H,Oo = C,H,O, + 3C0,. (3) 3C,E€,O, = C,H,,O,. I t has been previously shown that (1) and (2) take place almost quantitatively, although in actual preparation there.is much less in (1) owing t o the great instability of dihydroxymaleic acid in aqueous solu- tion.I n (2) a small quantity of an oxidation product is produced, and in (3) loss arises from the psrtial volatility of glycollic aldehydeHEYCOCK AND NEVILLE : THE FREEZING POINTS OF ALLOYS. 383 with alcohol vapour. From 100 grams of crystsllised dihydroxy- maleic acid, about 20 grams of crude ‘ sugar ’ are obtained, theory requiring 32 grams. I n former communications (Trans., 1894,65, 899 ; Byitish Association Beport, 1895) it has been shown that dihydroxymaleic acid may be formed from tartaric acid by exposure to air and light in presence of a ferrous salt. To a strong solution of a tartrate (e.g., Rochelle salt), R few drops of ferrous sulphate solution are added, and the mixture is ex- posed in an open dish to sunlight. After a short time, 8 yellow colour is developed, and, on adding caustic alkali, the beautiful violet colouu. characteristic of dihydroxymaleic acid is produced, and is intensified by the addition of ferric chloride. For the success of this experiment, three conditions are essential. 1. The presence of i ~ o n . In absence of ferrous salt, no colour tvhat- ever is obtained on the subsequent addition of caustic alkali and ferric or ferrous salt. 2. The presence of oxygen. No effect whatever is obtained if the exposure to light be made in a vacuum. 3. The presence of swnlight. Little or no colour is obtained after exposure to air in the dark. These conditions, therefore, show a resemblance to some of those which are necessary in vegetable growth. I n this connection, it may be of interest to ascertain whether dihydr- oxymaleic acid can be detected at any stage of vegetable life. It is just possible that the violet colour which has been obtained in certain cases with ferric chloride and ascribed to pyrocxtechin or phIoroglucinol, may, in reality, have been produced by dihydroxyrnaleic acid, which gives a similar colour reaction, UNIVERSITY LABORATORY, CAMBEIDGE.

ISSN:0368-1645    

DOI:10.1039/CT8977100375

出版商:RSC    

年代:1897

数据来源: RSC

摘要:

HEYCOCK AND NEVILLE : THE FREEZING POINTS OF ALLOYS. 383 XXXIX.-The Freezing Poifits of Alloys ~ontainin~y Ziiic and a ~ ~ o t h e r Metal. By CHARLES THOMAS HEYCOCK and FRANCIS HENRY NEVILLE. I NTRO DU CT I o N. THE present paper contains the results OF experiments most of which were carried out in 1894 and 1895, but some, including the greater part of the zinc-silver and the zinc-tin series, were performed in 1S96. The results are not so complete as we hard hoped t o make them, but in so large a subject it is hopeless t o aim at completeness, and the fact that an increasing number of students is now occupied with the cryo-384 HEYCOCK AND NEVILLE : THE FREEZING POINTS OF ALLOYS scopic study of alloys renders such an aim less necessary, for it may be hoped that one worker's results will cclmplement and correct those of anothef AT.Henri Gautier+ has lately published an investigation of the melting points of several alloys, including zinc-silver, that must cover the same ground as our own experiments on that pair of metals, but as me had obtained some reniarkable results with dilute solutions of silver in zinc before we were awnre that he was occupied with the subject, me have thought it worth mhilc to complete our zinc-silver freezing point curve. I n order that our work might have the value attaching to an independent investigation, we have not allowed our- selves the pleasure of studying his paper, although very possibly we might have been saved from some errors by doing so. The freezing points were determined by means of platinum resistance pyrometers identical with those described in a previous paper (Trans., 1895,67, 160).As the methods of using the pyrometers and reducing their reading to the centigrade-air scale are fully described in that paper, we content ourselves in thc present case wiLh stating t.he centi- grade tempera tures without explanation. Zinc is, in some respects, a inore troublesome metal to use as a solvent than any other, either of higher or lower inelting point, that we linve as yet employed ; for in working near 400°, we have been unable to find any substance which could be used to protect the surface of the molten alloy from oxidation. The paraffins, which we had employed up to the melting point of lead, were too volatile or decomposed at the higher temperature.The plan of introducing ,z jet of coal-gas into the crucible so that it impinged on the surface of the molten metal was adopted; but although oxygen was thus, to some extent, excluded from the crucible, the reducing action of the unlit coal-gas at so low a temperature as 400" was probably very slight. We do not, however, think that oxidation took place to such an extent as seriously to impair the accuracy of our results. The alloys were vigorously slirred by a plunging ring stirrer which just fitted the cylindrical crucible. This stirrer was of clay in a few of the earlier experiments, but afterwards we invariably used a stirrer made of gas carbon. In general, this stirrer was worked by a water motor, but in a few cases it was worked by hand. The experiments at temperatures below 500" were generally carried out in an improvised furnace which allowed of n somewhat more rapid rate of cooling than did Fletcher's furnaces.The base of this furnace was a, slab of fire-clay perforated by a circular hole about 2 inches in diameter, and the walls were formed by a cylinder of sheet asbestos. Resting on the top of this cylinder was a circular plate of thick sheet asbestos having a central hole. This formed the top of the furnace, and a * Covzpt. read., 1896 ; 123, 172-174.CONTAINING ZINC AND ANOTHER METAL. 355 cylindrical cast iron crucible with walls half-an-inch thick jusli fitted the hole in the asbestos top and was thus suspended axially within the furnace. The true crucible of plumbago, which contained the alloy, was a cylinder exactly fitting the inside of the iron crucible.The whole structure rested on an iron tripod so that a Bunsen burner could be placed underneath and raised until the flame more 01' less entered the hole in the base of the furnace. This arrangement gave us the power of heating rapidly, together with very steady temperatures, and some control over the late of cooling. We shall call this furnace A, to dis- tinguish i t from the Fletcher's furnace aucl from other arrangements sometimes employed. At the commencement of a series of experiments, a known weight of one metal was melted in the crucible and its freezing point determined. Successive known weights of the second metal were then added, the freezing point being determined after each addition.Except in the case of the silver-zinc zlloys, where me were forced to resort to chemical analysis, t,he composition of the alloy was deduced from the weights of metal used. This plan, at the comparatively lorn temperatures needed for zinc, and provided that care is taken t o minitnise oxidation, is pro- bably ns trustworthy as a n analysis, at all events when the series of experiments is not too prolonged. The results are given in tabular form and also expressed as curves. Each pair of metals has n separate table allotted'to it, and a t the head of the table me state the nature of the alloy and the weight used of what we may term the solvent metal. The first column gives the percentage by weight of the second metal present. The second column gives the atomic percentage of the second metal, or, in other words, the empirical formula of the alloy-thus a silver-zinc alloy having 20 atomic per cents.of zinc would have the formula Ag,,Zn,,. This column is calculated from column 1, and from the atomic weights of the metals. The third column gives the temperature a t which the alloy begins to solidify-the freezing point or f. p., as we shall, for shortness, term it. It is often easy t o recccl this temperature to 0*01", although the tmce temperature is no doubt rarely obtained so nearly as this. We think, however, that in certain cases our results would lose in accuracy by re- jecting the second decimal place, me have therefore usually retained it. The fourth column, the atomic fall, is obtained by dividing the total depression of the freezing point by the atomic percentage cif the second matal.It is clear that if, as should be the case for dilute solu- tions, the depressions are proportional to the concentrations, then the atomic fall ought a t least, for the same pair of metals, t o be a constant. This column is only given for dilute solutions. It is useful, because it386 HEYCOCK AND NEVILLE : THE FREEZING POINTS OF ALLOTS shows a t once whether the experiments are consistent with one another. It must be remembered, however, that, for very dilute solutions, the atomic fall necessarily appears to be irregular, as, from the method of calculating it, the experimental error is in such cases greatly magnified. I n the freezing point curves (pp. 404 and 422), the temperature is measured vertically upwards and is indicated by numbers placed at the side of the page or in some cases by numbers placed immediately below the line of the curve.The composition is indicated in atomic per- centages, the numbers being placed either along the top or bottom of the page, or in some cases by numbers immediately above the line of the curve. The plan of placing the numbers close t o the curve is convenient when it is necessary to make the curve of each pair of metals an independent figure having its own zero, as in Figures 4 and 15. The individual experiments are indicated in the figures by black dots lying on or near the line of the curve. It will be seen from the tables t h a t we in several cases give more than one series of experiments for the same metallic pair in which the starting point is the same pure metal. But the freezing points of the pure metal in two such series, obtained at different times and probably with different thermometers, are certain to differ a little.We there- fore, before charting these series, add to or subtract from every term of one of them the small constant quantity which is needed to make the f. p. of the pure metal the same in both; for example, in all the complete f. p. ciirves the f. p. of zinc is taken as 419.* The paper is divided into two almost independent sections. The first deals with those metals which, when added t o zinc, begin by lowering its freezing point, the second deals with those metals which raise the freezing point of the zinc. A reader can most readily obtain an idea of our results by turning a t once to the second part of each section in which the individual curves and their meaning are discussed, SECTION I.Me!ccZs wluiclb Lowey the Freezing Point of Zinc. Amongst the metals whose alloys we have examined, we find that the freezing point of zinc is lowered by tin, bismuth, thallium, cad- mium, lead, antimony, magnesium or aluminium. Our experiments with these metals are embodied in Tables I to VIII, and in Figures 1 to 1 2 (p. 404). * I11 all the experiments rangiiig over three years in time, and made with many different I,yrometers, t h e extreme divergence from the mean freezing point of zinc was +_ 0.7".CONTAINING ZINC! AND ANOTHER METAL. TABLE IA. CADAIIUN ADDED TO Zmc. Sei-ies 1. 200 panzs of Zinc. Unlit coal gas o n surfcccce o f metul.38'7 lIund-stiwing. 307 '25 ~ 307'56: 306-03 30 1 *05$ 296.30 285.79 286'48 250'9211 281.67 276'10 (264'62) Percentag!: of cad- mium by wcight. 0 0.259 0.990 2'479 5.167 14-11 16.38 19'74 22.83 28'42 35-36 35.36 40'59 45'48 49.42 52.91 56-11 60'27 63.75 > P Atomic percentage of cadmium. 0 0 '1 52 0.581 1'464 3.0,94 8.760 10'275 1257 14'74 18.83 24-22 Freezing point centigrade. Atomic fall. 418-50 417.86 415'82 411.69 404'28 381.80 374.98 371 '26 365.07 355'05 341-30 4.21 4 *61 4 %5 4.61 4 3 0 * Series 2. 129.3 gi'unts of zi1tc. 24.2 2 28-78 32'78 36.1 7 39.64 42'76 46-98 50.66 Y P 344'20 336,46 330'70 325.83 321 '99 31 7 7 7 31244 308'08 (264'42)t Series 3. 73.76 grunts o f Z i n c . 79 '60 50'0 51 '6 54.53 57-76 ti3.80 6S*'iO 68 ' j 3 ~~ ~ ~~ * From this point onwards, the cvnccntratioii is too great to render the atomic falls .i- The freezing point of the cutcctic mixture, a very steady temperature.$ Read with a layer of ragosiiie oil on the surface of the alloy. § Nuclei of zinc were dropped in, but seemed to have no effect in altering the f. p. 7l Raised alloy to a rcct heat after this reading, to make certain that all the zirie of any meaning. was melted.388 HEYCOCK AND NEVILLE : THE FREEZING POISTS OF ALLOYS TABLE 1 , ~ . ZINC ADDED TO CADMIUM. Swies 1. 2 5 0 grams of cadmium. Percentage of zinc by weight. 0 0.145 0.290 0-686 1'450 2.230 3.832 5 -708 8.760 12.72 18'42 25'69 3i116 Atomic percentage of zinc. 0 0-249 0.495 1.168 2.456 3.756 6,385 9'390 14-12 19-96 27.87 37.17 44)-'80 Series 2.225 grams of Cndmium. Freezing point centigrade, 320-55 319.88 319.33 317.32 313'77 309'51 302.74 295.03 284.41 273'10 267.04 28954 (264.56) 300.21 10.11 12'90 15.72 16.15 20.22 24.20 2$'50 26% 28-85 7 5 279.40 272.92 266'62 (264 '43) 264.76 (964.54) 264.54 269.06 (264 '50) With the exception of the eutectic points, which could be found by allowing the mixture to cool, and which were quite constant for many minutes, all the freezing points of alloys, rich in both cadmium and zinc, were difficult to observe exactly. They were read with the aid of a metronome to mark the rate of cooling; there was no period of absolutely constant temperature, but, at the point recorded, the rate of cooling suddenly became three or four times as slow as it had been until then.CONTAINING ZINC AND ANOTHER METAL.389 TABLE IIA. ALIJMINIUM ADDED TO ZINC. 400 grams of Zinc. Coal gas buwzing over the surfucs of f i e metal. Percentage of alu- minium by weight. 0 0'41 0-82 1'23 2 -03 3-20 5'47 7 '64 14.53 18'87 18'86 25 '06 30.37 36'22 9 'il Atoniic percentage of aluminium. 0 0 '99 1'96 2.91 4'76 7.41 12-28 16.67 20 *'64 29'14 36'00 51.34 57'87 Freezing point centigrade. 418% 414.5 410'4 407'7 401 -4 392'2 (380*6)* (380'9)' 404'9 418'4 447.3 466'1t 464'9x 492% 508'4t 525 '4 Atomic fall. 4.13 4.11 3.76 + Very steady eutectic temperatures. $ The f. p. of residue. The mass was nearly solid before the Extracted a portion, weighed it, and continued the experiment with the residue, first of these two points was reached. TABLE I1 B.ZINC ADDED TO ALUMINIUM. I75 g?*ams of Aluminium. Percentage of zinc by weight. 0 0 '90 2'34 3 '42 5'83 8 -76 11.98 I 8 *23 25-22 31-10 38'39 44-27 49 -1 3 56.39 6l'bO 65-80 53%5 Atomic percentage of zinc. 0 0'374 0'981 1-44 2-50 3.82 5'33 8 -44 12-24 15.73 20.49 24-73 28'54 32'*k 34.84 44'31 39'% ~ Freezing point centigrade. 654'5 652.5 650'4 648'7 644.9 639-5 634.4 623.2 613'0 598.7 584.5 571 '1 560 '2s 542-211 541 *4TT 530.8 518.2 54;:5 Atomic fall. 5 *35 4.18 4 -03 3'84 3-93 3 '77 3.71 3.64 3 -55 3 -41 0 After this reading, a weighed amount was extracted, and the experiment con- 11 After this reading, we extracted a weighed portion. VOL. LXXI. E E tinued with the residue. I t will be seen that the f. p. was unchanged. The f. p. of the residue.390 HEYCOCK AND NEVILLE: THE FREEZING POINTS OF ALLOYS 1 Series 1.BISMUTH ADDED TO 500 GRANS OF ZINC. In a clay cruci6le placed in the a x i s of a smcd i v o n block. Stirred by ct Coal yccs burning o n the stwface of the metaZ clay ring stirre?.. during cooling. Platinum pyrometer in porcelain tu6e. Percentage of bis- muth by weight. 0 0'439 0'826 1.217 1-614 1 -99 2 '44 6-12 9 -48 Atomic percentage of bismuth. 0 0.139 0.262 0.386 0.514 0.635 0-783 2.01 3 '21 Freezing point cen t.igrade. Atomic fall. 418.64 417.94 417'37 416-78 416.31 415.84 415'73 415.66" 415.65* 5 *03 4.85 4'82 4-53 4.41 I I 1 Seiaies 2. Bismuth added t o 258 grams of Zinc. In f u r n a c e A . Coal g m , unlit, over s w f a c e of the metal. Platinum pgrorneter in thin glass tube. Carbon r i n g stirrer.0 0-200 0'591 2.020 2 '36 9 -51 17.13 26.67 38 *35 44-84 50.92 55.79 59-93 63-20 0 0'063 0.187 0.645 0.756 3.20 6-11 10 '2s 41 8 *80 418'46 417.71 415.93 415.93 415'93 415.95 > ) 5 *4 5 '8 Saturated. Y Y > t J Y Seyies 3. Bismut?b added to 160.75 grams c,f Zinc. Co,bditions the same us in Series 2. 16.38 20.38 24 '63 28 '44 32'02 35.11 416'20 416.50 416'70 416.80 416'86 416.90 * In these last two readings a trace of surfusion was noticed.CONTAINING ZINC AND ANOTHER METAL. 391 From 6.11 atomic per cents. of bismuth to the end of Series 3, each freezing point is an extremely steady temperature ; in fact, the tempera- ture was watched for nearly five minutes after reading the freezing point and no fall in temperature noticed, We did not venture to allow the mass to solidify completely, lest the metal in setting should crush the glass tube of the pyrometer.A very rapid stir was maintained during Series 3. A t the end of Series 3, the alloy, after being well melted, was allowed to cool slowly, and the ingot of metal was finally extracted from the crucible. It weighed 431 grams, and there was also a little on the pyrometer stem and the stirrer. The weight of the metals used was 437 grams. The alloy consisted of two layers, the lower about twice the amount of the upper. They were easily separated by a blow from a hammer. The constants of the pyrometer were found to be the same at the beginning and end of the experiments, hence the slight upward creep of the freezing points along the flat of the curve is probably a real phenomenon, perhaps due to an impurity in the bismuth.TABLE IIIB. Conditions the same as in Tuble III A, fleyies 2 and 3. ZINC ADDED TO 300 GRAMS OF BISMUTH. Percentage weight of zinc. 0 1.336 1.954 3'218 4'116 7'142 8'633 11 '63 14 '68 15.49 17';5 ZZ*'iO 26'15 Atomic percentage of zinc. 0 4'12 5.95 9 -55 12 '00 19'63 23-08 29'47 34.'60 36.78 47 '62 52'93 Freezing point centigrade. 269'37 261 '81 258'60 254.51 254.37 343'0 358.1 387.3 409-4 41 6 '9 417.8 417.8 41 7.9 417.2 416% 388-3 Atomic fall. 1.835 1.810 Saturated. 2 ) After each addition of zinc, it was necessary to heat the alloy to the melting point of zinc to bring about solution. I n the freezing points, down to 12 atomic per cents. of zinc, surfn- aion was generally noted, sometimes to the extent of 2'.The point at 12 atomic per cents. of zinc was a very steady tempera- ture. Here the rate of cooling mas carefully watched from 50' aboye the recorded temperature, but no higher freezing point could be found. E E 2392 HEYCOCK AND NEVILLE : THE FREEZIKG POINTS O F ALLOYS A t 19.63 atomic per cents. of zinc, the freezing point was somewhat fugitive ; this is always the case a t the first points on the branch of the curve ascending from the lower eutectic flat towards the melting point of the less fusible metal. The experiments of Table I11 B were carried out with a sample of bismuth, believed t o be specially pure, which was used by Griffiths in his determination of the freezing point (PM. Fg-ans., 1891, A, p. 150). He then got 269.22' as the mean of his results.It is inter- esting to note that our number, obtained without any special attempt to arrive a t a standard result, differs from his by only 0.15'. His platinum thermometers were of a different type from ours, and the conditions of the experiment in other respects not the same. We think it very doubtful whether, even a t these moderate temperatures, two mercury thermometers would have given so close an agreement. TABLE IVA. TIN ADDED TO ZINC. Series 1. 700 gvams of Zinc. A n eady series of experiments. The conditions not specially noted. Percentage weight of tin present. 0 0.549 1-088 1.795 3.152 3-450 4'873 Atomic percentage of tin. 0 0.305 0.606 l*OO4 1,772 1.944 2.763 Freezing point centigrade. 419.57 417.82 416.18 414.14 410.53 409'82 406.40 Atomic fall.5.7 5.6 5-40 5-10 5.02 4-76 Seiies 2. 150 grccrns o f Zinc. In furnace A . Carbon stirrev. 0 3'23 6-25 11.77 16 *67 23-08 2957 35'04 41'14 49'07 55-12 0 1.81 3 5 6 6-88 9.98 14-26 18-88 23'02 27-94 34.83 40 -53 418.86 409.80 402.61 393.16 387 *38 380.56" 374.81 370'07 364.37" 355.62 347 5 6 5 '00 4 $6 * After these readings, the crucible was too full ; a. portion of the alloy was there- fore extracted in a molten state, weighed, and the experiment continued with the residue.COKTAINING ZINC AND ANOTHER METAL. 393 Percentage weight Atomic of tin present. of tin. TABLE IV A.-COlLti?tUed. Series 3. 200 gl.anuzs 0s ZillC. 1% furnace A . Unlit coal gem. P y r o m e t e ~ i m a glass tube. Atomic fali. 0 0.356 0.860 1.445 2.120 0 0.198 0'479 0 -806 1.187 418'15 417.04 415.52 41 3 -95 412.18 5.60 5 -49 5.21 5.03 ~~ Series 3 was carried out later than any other work described in the paper, as a check on the large atomic falls of Series 1.The last reading of Series 3 was repeated several times during an hour, and remained unchanged, hence there does not appear to be any loss of tin by oxidation. This series is not utilised in drawing the f. p. curves. TABLE IVB. ZINC ADDED TO TIN. 150 g r a m s of Ti?&. Purnace A , &c., as before. Unlit cocd gccs o n suqface. Percentage weight of zinc present. Atomic percentage of zinc. Freezing point centigrade. 10.71 11.65 d158 16.43 19.68 2i*'41 27.37 30.77 34.93 38.67 9 , 1 4 0 8 17.80 19'23 2d*'6l 2d*'82 26'18 30'64 3i152 40'45 44'45 49'18 53'20 I ) 197.79" 197'94 228'64t 228-77t 197'90 234.82 245.61 260 *80$ 281'04 197.77 312'40 323'72 335.47 342'70 § 2 9 i w * A very steady temperature..t. A slight halt in the cooling here. $ From here onwards the freexing points are well marked. § At the end of the experiments, the alloy was poured out of the crucible, and A little powder mas noticed with the metal. This may have been No higher point could be detected. examined. oxide, but mas more probably carbon from the stirrer.394 HEYCOCK AND NEVILLE : THE FREEZING POINTS OF ALLOYS TABLE V. LEAD ADDED TO 550 GRAMS OF ZINC. In Salamander crucible in cb smalZ PZetcher lilt& fuwzace. coal gas bumimg on the s w f x c e during coolimg. A little Percentage weight of lead. Atomic percentage of lead. Freezing point centigrade. Atomic fall.0 0-315 0'628 0.939 1.25 2 *01 4.95 15.15 0 0 . l o 0.20 0.299 0'398 0'646 1 '62 5-35 419-22 418'7.2 418'16 417.74 417.73 417.73 417'63 417'63 5 '0 5 '3 4.95* -t. ~~ ~~ * This, and all the followisg freezing points, are the same, because the zinc is These freezing points of the saturated alloy were very constant saturated with lead. temperatures, and became more constant with each addition of lead. j. The stationary temperature here lasted 13 minutes without change. TA4BLE VI. ANTIMONY ADDED TO 250 GRAMS OF ZINC. Coal gas burrning over the surface of the metal. Percentage of auti- mony by weight. 0 0.273 0'669 1 -26 > Y 2 ')2)3 3 *37 4.47 Atomic pepcentage of antimony. 0 0.149 0.365 0?99 1 *;3 > > 1'86 2.49 Freezing point centigrade. 418.78 418.10 417.02 416.66 414.80 414.52 414'67 412% 412.57 412.65 Atomic fall.4.5 4 '8 5.8 4.98 6 '3$ 5 *1 4.84 § $ The experiments were resumed here after a night's interval. 3 A very steady temperature. Before the reading, the alloy was heated to a red heat to ensure the solution of the antimony.CONTAINING ZINC AND ANOTHER METAL. 395 ~ 419 416.62 414.35 410-04 408.84 TABLE V1I. THALLIUM ADDED TO 250 GRAMS OF ZINC. Carbon stirwr. Coal gas b w n i n y o n tlhe surfcice of metal. Percentage of thal- lium by weight. Atomic percentage of thallium. Freezing point centigrade. Atomic fall. 0 0.392 1.22 2-85 3.77 5-87 0 0'126 0-393 0.831 1 '241 1'962 418.77 418.18 416'79 416.51 416'46 416-41 4'7 5'0 Saturated. TABLE vm. MAGNESIUM ADDED TO ZINC. Seyies 1. 250 gvurns of Zio~c.Percentage weight of magnesium. Atomic percentage of maguesium. Freezing point centigrade. Atomic fall. 0 0.157 0.320 0.574 0'972 0 0 '42 0'854 1'53 2 *57 5'64 5 '67 5.77 5-89 se2vies 2 . 250 grams of Zinc. 0 0.138 0'364 0.685 1'503 0 0 *37 0.975 1'818 3'936 419.05 417.26 413.78 408'92 395'21 4'84 5 '41 5'57 6 '06 Series 3. 250 grams of Zinc. Ptcre hydrogen over suyface of ulloy. 0 0'405 1 '246 2'361 0 1.08 3 .la 6 '10 41.9'02 413-39 401 *60 382'17 5 '21 5 '48 6'04396 HEYCOCK AND NEVILLE : THE FREEZING POINTS OF ALLOYS TABLE VII1,-continued. Xeries 4. 192 gr-arns of Zinc. over surface of metal. In small PZetchr blast furnace. Curreiit of coal gas burning Percentage weight of magnesium. 0 0-332 0'819 1 *486 2,058 3.360 ) ¶ Atomic percentage of magnesium.0 0.887 2.17 3 -89 5 -34 8-55 > Y Freezing point centigrade. 419.0 413.93 406'41 395.13 387'44 369'61 369.74 Atomic fall. 5 *72 5'80 6 -14 5'91 5-78 The magnesium was in sticks from the Patricroft factory. It is a t once wetted by the zinc, and dissolves easily at temperatures but little above the melting point of zinc, and with no apparent evolution of heat. Zinc-Cadmium. Figure 1 (p. 404) gives a complete freezing point curve for all mixtures of these two metals. It may be regarded as a fairly typical one for metals which do not combine chemically, and which are soluble in each other in all proportions. It shows that the addition of cadmium to the zinc lowers the f . p. until about 73.5 atomic per cents. of cadmium are present when a minimum f . p. of 264.5" is reached, and that further addition of cadmium raises the f.p. continuously until with 100 atomic per cents, of cadmium the f. p. of that metal is reached. The determination of the composition of the eutectic alloy, that is the alloy of lowest freezing point, was difficult in this particular case. The freezing points near, but above the eutectic, are always somewhat fugitive temperatures, and in the present case, the chance of oxidation during t h e prolonged series of experiments makes our knowledge of the composition of the alloy a little uncertain. It is quite possible that all the causes of error, taken together, may make our estimate wrong by more than one atomic per cent. I n other words, the experi- ments do not contradict the supposition that the eutectic state occurs at ZnCd,, but this is almost certainly a coincidence, like a similar case we have observed for silver-copper. There can be no doubt that the eutectic alloy is nothing but that particular mixture of the two metals from which, when liquid, they would both separate in the solid form atCONTAINING ZINC AND ANOTHER METAL.307 the same temperature; there is, therefore, no reascn for expecting it to be a chemical compound. In fact, although from the imperfection of our experimants we could not trace the curve close to the eutectic state, and have, therefore, drawn the figure as if the two branches passed into each other here with a continuous curvature, it is almost certain that, with perfect experiments, this eutectic point, like others, would be found to be an angle in which two entirely independent branches of the curve cut each other.The branch which starts from the f.p. of pure zinc, may be regarded as the f. p. curve of zinc, holding cadmium in solution, while the other branch is the f. p. curve of cadmium, holding zinc in solution. In the upper part of each branch, there is no doubt that pure zinc or pure cadmium respectively freeze out at the f. p,, and this may, perhaps, be the case throughout the whole of each branch, but the fact has not been verified by experi- ment. We have not been able t o find freezing points on either branch below the eutectic point; the curves, in fact, seem to end at their intersection, but if it were possible to produce a state of superfusion in an alloy containing a little more zinc than the eutectic, we might, by dropping in a nucleus of cadmium, obtain a point on the cadmium branch below the eutectic. We believe that some experimenters, using other binary mixtures, have thus traced the two branches a little way below the eutectic point.* The f.p. of the eutectic alloy is more certainly determinable than its composition, for it can be found as a second freezing point of alloys of various compositions. For example, if we take an alloy containing '50 atomic per cents. of zinc, and therefore more zinc than the eutectic, melt it completely, and allow it to cool, we shall, a t 30S0, find a f. p. at which zinc, or, a t all events, something containing more zinc than the liquid, begins to separate as a solid. This process will go on as the alloy cools, until, by the continual separation of solid matter, the still liquid portion has reached the composition of the eutectic alloy.The temperature will now be 264.5', and will remain constant until every particle of the alloy has solidified, for the liquid is now saturated both with zinc and cadmium, and these metals will freeze out in the same proportions as those in which they are present in the liquid. If we start from an alloy on the cadmium side, a similar pro- cess will take place. Our figure shows the horizontal line of eutectic freezing points obtained in this manner. The indications of chemical combination between the zinc and the cadmium are slight, if, indeed, such indications exist. But at Cd,Zn, there is a perceptible shoulder t o the curve, that might be regarded as a much degraded intermediate summit. This may be interpreted as indicating the existence of a compound CdZn, which, when melted, is * Dahms, A m .Phzts. Chenz., 1894, 54, 486.398 HEYCOCK AND NEVILLE : THE FREEZING POINTS OF ALLOYS very largely dissociated into its constituent metals. However, when we come t o the consideration of the zinc-tin and zinc-bismuth curves we shall see that another explanation of this feature is possible. If the compound CdZn exists, then when alloys with more than 50 and less than 74 atomic per cents. of cadmium begin to solidify, we should expect this compound t o separate as a solid. If it were possible to collect the first precipitate free from mother liquid, we might settle the question, but the practical impossibility of doing this has caused 11s to abandon such methods OF attacking the problem.A proof, to our minds almost conclusive, against the view that a solid compound of the formula CdZn exists, lies in the fact that the temperature, after freezing had commenced at 50 atomic per cents. of cadmium, was not particularly steady, so that the alloy cannot have solidified homogene- ously. I n fact, at 50.7 atomic per cents. of cadmium, the eutectic temperature of 264.5" was well marked. This could not have been the case if a compound CdZn had been forming, for, in that case, there would have been little or no liquid left a t the eutectic temperature. Zinc-A Zuminium. Figure 2 (p. 404) gives a complete freezing point curve for these two metals.It is plotted on the same scale as figures 1, 3, 4 and 5 , but to economise space the f. p. of zinc and therefore the whole curve is shifted to a lower point on the page. The curve is essentially similar to that of zinc-cadmium. The eutectic alloy has a melting point of 380.5' and contains 11 atomic per cents. of aluminium. We do not think that the curve shows an indication of chemical com- binations in any propwtion. The very slight tendency to an inflexion near 40 atomic per cents. of zinc is very probably due to the fact that near here the two series of experiments starting from opposite ends of the curve meet. The losses of metal from oxidation might be expected t o produce a fictitious raising of the curve which starts from the zinc elid and to lower that starting from the aluminium end, in the exact way shown on the curve.Alder Wright * says that some alloys of these two metals separate into two liquid layers on standing for some time, but the form of our curve makes us doubt the accuracy of this statement. If it were so, the curve would resemble the zinc-bismuth curve in form. The zinc-cadmium and zinc-aluminium alloys were amongst the earliest that we examined by means of platinum resistance pyrometers, and the experimental error is perhaps larger than in the case of the other experiments described in the present paper. * PYOC. Roy. xoc., 45.CONTAINING ZINC AND AKOTHER METAL. so9 Zinc -Bismuth. The zinc-bismuth curve, Figures 3 and 6 (p. 404), affords a typical example of the process of solidification for an alloy of two metals which are only partially miscible with each other.The curve shows that when bismuth is added to zinc the f. p. of the zinc is a t first lowered by an amount which is nearly proportional to the weight of bismuth present, until 0.65 atomic per cents. bismuth have been added. A further addition of bismuth produces absolutely no effect on the f. p. until as much as 6 3 . 2 atomic per cents., that is, 84.5 per cent. by weight, have been added. A still further addition of bismuth produces a fall in the f. p. almost as rapid as that caused at first, and at the same time the freezing points, from being extremely steady stationary t emperatures lasting for a long time without change, become very fugitive. After 80 atomic per cents. of bismuth, we could no longer detect these freezing points, but the eutectic f.p., again a very steady temperature, began t o show itself. We have drawn, as a dotted line, a hypothetical continuation of the f. p. curve to the point where it meets the other branch. We are aided in determining the exact point of intersection by the fact that it must lie on the horizontal line of eutectic freezing points which are so easily determined. The curve shows that the intersection is close t o 92 atomic per cents. of bismuth. Alder Wright * found that when alloys of zinc and bismuth were allowed t o remain for a considerable time at a constant temperature of 650”, they separated into two layers containing respectively 2.3 and 85.3 per cent. of bismuth by weight. We have now to account for the long upper flat on the curve, reach- ing from 0.65 to 63 atpmic per cents.of bismuth. This flat records the fact that between these limits the freezing point is quite inde- pendent of the composition of the alloy. But there is another peculiarity of this region. It is that each freezing point is a well- marked steady temperature remaining quite unchanged until a large amount of solid has been formed. I n some cases, however, we watched the thermometer until the temperature of the mass began to fall again, and this took place before the alloy set to a solid mass. I n this latter feature only does the process of solidification differ from that of a pure metal. We have already, in a paper about to appear in the Tmnsactions of the Royal Society, discussed a similar phenomenon.? We shall, theref ore, here treat the point very briefly.The existence of the flat, and also the extremely steady temperature of each freezing point on it, are + See also Neville, Scienec Progress, iv., p. 4. * Proe. Boy. soc., 50, 388.400 HEYCOCK AND NEVILLE : THE FREEZING POINTS OF ALLOYS due t o the alloy in this region consisting of a pair of conjugabe liquids -zinc saturated with bismuth and bismuth saturated with zinc. The composition of these conjugates is given by the atomic percentages at the ends of the flat. Each of these liquids remains unchanged in composition throughout the flat, but, as the total percentage of bismuth increases, the alloy richest in bismuth grows at the expense of its conjugate. Moreover, both conjugates have the same freezing point and therefore, as the freezing proceeds, the residual liquid will still consist of the same two alloys. It will consequently not fall in tem- perature until one conjugate has wholly disappeared.When the con- jugate richest in zinc has gone, either through the separation of solid zinc or the addition t o the mixture of bismuth, we have a state of affairs represented by the second sloping line. Here, most probably, solid zinc is separating out of a solution of zinc in bismuth, and from the slope of the line it would appear that the latent heat of solution of zinc in such a mixture is almost the same as the latent heat of fusion of pure zinc. One of us has already drawn attention to the fact,* not then verified, t h a t if such a pair of conjugate alloys be raised to a sufficiently high temperature it must become a uniform- liquid.I n fact, starting from the two ends of our upper flat, a dome-shaped curve could be drawn giving the critical temperature of complete miscibility of every alloy of zinc and bismuth. Whether there would he a well- marked thermal change a t the moment when a homogeneous alloy began, through cooling, to separate into conjugates is doubtful : we have not hitherto been able t o detect the phenomenon by means of our thermometers. Alder Wright's values for the composition of the two conjugates a t 650' give two points on the critical curve, and Spring and Romnnoff f have lately found that for zinc-bismuth the summit of the critical curve is near 850', whilst for the similar case of zinc-lead it is near 950'.Our curve seems to show that the change from the homogeneous liquid t o the pair of conjugates and vice ve?*scc is a very sharp one at the freezing point ; hence the two sloping parts of the curve meet the flat in angular points. This is not the case for all alloys which separate into conjugates. It ought to be possible t o continue the flat to tbe left beyond the angle at 0.65 atomic per cents. of bismuth, second or eutectic freezing points being found for alloys with less than this proportion of bismuth corresponding with the moment when the still liquid portion of each alloy has, by the separation of solid zinc, reached the state .of being saturated with bismuth. Unfortunately, we omitted to look for such points dux ing our experiments.* ,Science Progress (Zoc. cit. ). t Zeit. anorg. Chenb., 1896, 13, 29.CONTAINING ZINC AND ANOTHER METAL. 401 Zinc- Tin. I n Figure 4 (p, 404), me give the f . p. curve of these two metals plotted on the same scale as the zinc-bismuth, and lying nearly between the same limits of temperature. There is here no angle except that which always occurs where the two branches of the curve meet a t the lower eutectic point. The changes in curvature are all gradual, as we should expect in the case of two such metals as zinc and tin, whose alloys do not, under any circumstances, separate into conjugate liquids. I n fact, the zinc-tin resembles the zinc-cadmium curve, but the first ten atomic per cents. of tin produce a more rapid curvature than is the case with cadmium ; and a shoulder a t 50 atoms, which is barely perceptible in the cadmium curve, is well marked in that of tin.The shoulder is some- what exaggerated in the figure, owing to the fact that the two series of experiments which start from opposite ends of the curve, approach each other here, and through therinometric errors, or loss of metal by oxidation, do not quite meet. We cannot however see, in any feature of the curve, an indication of the existence of chemical compounds such as the SnZn, that Alder Wright believed to exist. Considered from the point of view of the physical theory of solu- tion, it would appear that, as the solution becomes more concentrated, the atoms of tin tend to form larger aggregates to a greater extent than do those of cadmium.I n fact, zinc-tin approximates more to the condition of zinc-bismuth than does the cadmium alloy. We are per- haps too much in the habit of regarding as a perfect solution any liquid mixture which does not separate into conjugates. On the con- trary, there is probably an infinite series of gradations between that perfect state of solution in which the dissolved body, whatever may be its relation t o the solvent, is divided into single atoms or molecules, and that in which it is on the point of separating in drops from the solvent liquid. We may expect to see these degrees of dissolution reproduced in the freezing point cizrves as well as in other physical properties. I n connection with this subject, it is not without interest to com- pare the preceding curves with Figure 5, which is the ideal f.p. curve for zinc containing another metal in solution. This curve is calculated from Le Chatelier’s equation, 2 log, x=h (; - 8 ) 1 where x is the concentration of zinc (the atomic percentage divided by loo), X is the latent heat of fusion of an atomic weight of zinc, and 8, and 8 are the freezing points, reckoned from absolute zero, of pure zinc and of the alloy respectively. The equation assumes that the molecular402 HEYCOCK AND NEVILLE : THE FREEZING POINTS OF ALLOYS condition of both metals remains the same throughout as it was in the dilute solution, and that the heat of solution of the zinc in the alloy a t the lower temperature remains the same as the heat of fusion of the pure zinc at 419". The rapid divergence of the real curves from Figiire 5 shows how far these assumptions are from being true.ThaZlium, Lead, Antimony, Jfc~gnesium, and X c k d in, Ziizc. We have (No. 2) carried our experiments on the addition of thallium or lead to zinc very far, for Figures 8 and 9 and Tables VII and V show that these two curves, if completed, would closely resemble that of zinc-bismuth. In all three cases, the addition of the second metal soon causes the alloy to separate into two conjugates, and we have the phenomena of the long upper flat repeated. So far as our experiments enable us to decide, we see from Figure 9 that zinc is saturated with thallium a t the freezing point, when 0.45 atomic per cents. of the lattey metal are present, and t h a t the f. p. of the zinc is thereby lowered by 2.3'.Similarly, Figure 8 shows that the zinc-lead alloy, at its freezing point, is saturated with lead when 0.26 atomic per cents. of lead are present, the temperature on the flat being 1 . 6 O below the f. p. of pure zinc. The zinc-antimony curve of Figure 7, although similar in appearance to the two preceding, records a different phenomenon, Here, the angle at 412.6" and 1.25 atomic per cents. of antimony gives the lower eutectic f. p. and the composition of the eutectic alloy, and, as in the case of zinc-aluminium, there must be another branch starting from the eutectic angle and running up towards the f. p. of pure antimony. This curve would probably be worth completing. I n drawing the antimony curve, but little weight is given t o the second reading a t 0.365 atomic per cents,, as the atomic fall deduced from i t is obviously inconsistent with the others. Similarly, the second and third readings at 0.799 atomic per cents., taken after a night's interval, and after re-melting and heating the alloy to a red heat, have not so much value attached to them as the first.Zinc- Magnesium. This curve was not traced to saturation ; in fact, the part examined is nearly a straight line. A peculiarity of this curve lies in its steep- ness. From the beginning to the last experiment, the atomic falls caused by magnesium are greater than those due to any other metaJ. This is more remarkable, as the magnesium might be expected to oxidise more readily than the other metals, and losses from this cause would make the observed depressions too smdl.CONTAINING ZINC AND ANOTHER XETAL.403 Zinc- Nicke I . A very small addition of nickel to zinc lowers t'he f. p., but the limit is soon reached, and further additions of nickel produce no effect. The depression was too small to admit of trustworthy measurement. Dilute Solutions and the Heut o f Pusion of Zinc. In Figures 6 to 12 (p. 404), the dilute solutions of the metals, whose alloys with zinc we have discussed above, are given on a larger scale than the complete curves This plan enables us, as in the case of antimony, to reject unsatisfactory observations and to read off the mean atomic fall. I f we wish to deduce from our results the latent heat of fusion of zinc, we are warned, by the rapid way in which the curves of Figures 1 and 4 rise above Figure 5, that i t is useless to consider solutions containing more than one or two atomic per cents.of dissolved metal. But dilute solutions present special difficulties, We have first the difficulty that the temperature differences measured are small com- pared with the probable error of experiment. This shows itself in the irregularity of the atomic falls for very dilute solutions; but when the conditions are favourable, as in the bismuth, the lead and the last of the tin series, we think the temperature differences of the early parts of each series, found probably within an hour of each other, may be trusted to within a very few hundredths of a degree. A more serious difficulty is the tendency for the observed atomic falls in very dilute solutions to be abnormally large.This peculiarity is evident in the tin experiments, Table IVA (p. 392). Series 3 of this table was carried out much later than the others t o verify the fact. We have here to deal with a phenomenon that has been one of the main causes of error in modern cryoscopic work, and which was first dis- cussed in a systematic manner by Nernst and Abegg.* As we do not in our work surround the alloy by a bath of constant temperature, rz '' convergence temperature " does not, strictly speaking, exist, but since the furnace and the other bodies which are in thermal communication with the alloy are at a lower temperature than it at the moment of reading the f. p., we may regard the quantity t' - to in their formula T fc t' = F - -- (t' - to) " K as necessarily positive.It follows that t', t,he observed f. p., is lower than To, the true f. p. or equilibrium temperature. This applies to pure zinc as well as to the alloys, but Nernst and Abegg found that liT for pure water was much greater than for a solution, while k was probably the same for both. For similar reasonp, Rfor a pure metal would probably * Zeit. phgsik. (?hem., 1894, 15, 681. + Where to is the convergence temperature, and R and k are constants depending on the nature of the substance.406 HEYCOCK AND NEVILLE : THE FREEZING POINTS OF ALLOYS Atomic per cents. be greater than for an alloy. I n other words, our observed depressions must be greater than the true ones. The resulting error appears to affect the atomic falls of dilute solutions most seriously.It is clear, therefore, that we cannot hope to obtain a very accurate value of the latent heat from the experiments we have hitherto made. But it would not be impossibl2, by modifying our arrangements, to find K and k, and so largely increase the accuracy of the results. The question now arises how to deduce the most probable value of the atomic fall from the numerous observed values. If me take the arithmetical mean of the atomic falls given in the tables, me attach undue importance t o the experiments on very dilute solutions where the experimental error is large. We think it a good plan to divide the arithmetical mean of the depressions, taken from column 3 of the tables, by the arithmetical mean of the atomic percentages taken from column 2.We thus give t o each experiment a weight in the result proportional to the temperature interval measured in it. We must confine ourselves to those early experiments for which the f. p. curve is a straight line, Thus, for bismuth, me have, from Table IIIA (p. 390), Series 1 and 2, the following. Depressions o f f . 1'. 0.139 0'262 0.386 0.063 0.187 0.70" 1'27 1% 0 *34 1'09 This gives a mean depression of 1.052" for a mean concentration of Applying this method t o each of t.he other metals, we get the 0.2075 atomic per cents., or an atomic fall of 5.07. following table. Metal. Extreme atomic per- centage. Mean atomic percentage. Bismuth ............ ,, from curve Lead .................. Thallium ............ Tin .................. Magne siuni ......... Cadmium ............ Aluminium .........Antimony * ......... 0.386 0.799 0.500 0'200 0 '393 1.187 0.975 1'464 0.99 0.2075 0.4377 0.500 0'150 09595 0.655 0.655 0.732 0 '99 Mean depres- sion. 1.052" 2'247 2 '60 0'78 I .285 3.497 3-572 3.377 4-10 Mean atomic fall. 5-07 5-13 5-20 4'95 5'34 5.45 4'61 (4'14) (5-20) * Here we have taken ths mem reading a t 0-365, and also the mean reading a t 0.799, otherwise too much weight would have been given to these concentrations.HEYCOCK AND NEVILLE. Journ. Chem. Soc., April, 1897.HEYCOCK AND NEVILLE Journ. Chem. Soc., April, 1897. Atomic Peroents. ZINC AS SOLVENT. The numbers immediately belo he line of each curve give the F. P en tigrade Temperature. - Atomic Percents.CONTAINING ZINC AND ANOTHER METAL. 405 The last column in this table shows a good deal of discrepancy between the mean atomic falls for the various metals, the most diver- gent being the cases of magnesium, cadmium, and aluminium.The large atomic falls shown by magnesium in zinc have a different char- acter from those of tin. It will be seen from Table VIIT (pp. 395-6) that they have been verified by repeated experiment, and that, instead of diminishing, they are either constant or increase with increasing con- centration. A possible explanation is that the magnesium is combining with t%e zinc, but we do not feel satisfied that we have here the true explanation. I n our early experiments, in which tin was used as a solvent, cadmium gave a smaller atomic fall than most other metals, so that we may perhaps regard it as a peculiarity of this metal to do so.But, in some experiments in which cadmium was dissolved in zinc which had been contaminated with about 1 per cent. of platinum, we obtained for cadmium the atomic falls 4.8 and 4.9, which are not very far from the average for other metals. The case of aluminium is different, in tin it gives only half the normal depression, and here it deviates so much from the others that we think we are justified in rejecting its value as, from some unknown cause, too low, I n the above table, we have placed a bracket round the atomic falls that we do not propose to use in getting the final mean. The remaining numbers must be regarded as CL priori equally prob- able, aQd therefore their mean ought to be found by the method of least squares, but their accuracy hardly justifies so refined a method.We have, therefore, taken their arithmetical mean, which is 5.11". As this is a t a mean concentration of half an atom, we may use the equa- tion for dilute solutions to obtain the latent heat. Here, 66 = 5.11' the atomic fall, 8 = 273' + 419" = 692' the melting point of zinc on the absolute scale, and X is the latent heat of fusion of an atomic weight of zinc. From these data, we find that the latent heat of fusion of a gram of zinc is 28.33 calories. This number agrees very well 1vit.h Persons' valae of 28.13, but it would have been easy, by leaving out cadmium or magnesium, or by using the numbers from rather more concentrated solutions, to obtain a result which differed by several per cents. frorr the above, se = 0.0198 ty/x VOL. LXXI.E ' F406 HEPCOCK AKD NEVILLE : THE FREEZING POINTS OF ALLOYS SECTION 11. Hetals which q*aise the Bkeexing Point of Z i n c . -We have found that silver, gold, copper, and perhaps platinum, in however small a quantity they are added to zinc, at once raise the f. p. and apparently cause the whole mass of metal to solidify above the f. p. of pure zinc. In the case of gold, copper, and platinum, we have only studied dilute solutions, but all alloys of silver and zinc have been examined. We sliall, therefore, begin by discussing the experiments with zinc-silver. The results are given in Table IX, and in Figures 13, 14, and 15 I n the first four series, in which the temperature rarely rose so high as 600", me determined the composition of each alloy by calcula- tion from the weights of metal which had been placed in the crucible, but this method began t o be untrustworthy in series 3 and 4, on account of the oxidation of the zinc.In series 9, also, which, chronologically, was an early series, the composition mas deduced from the weights added, and it is a little curious that when once the zinc has been stirred into the molten silver, there is, in dilute solutions of zinc in silrer, very little further oxidation. But in the middle part of the curve, the burning away of the zinc was continuous, and it became quite clear that the composition of the alioy must be determined by malysis ; we therefore, a t first, after every few readings of the f. p., 2nd finally just before each reading, extracted samples of the alloy for analysis. This was done by means of pipettes made from somewhat thick-walled Jena glass tubes, One end of the tube was thickened rind drawn out to an almost capillary opening.The lower part of the pipette was heated to a faint-red heat, and dipped in the alloy a t a moment when the latter was 20 or 30 degrees above its f. p. The necessary amount of alloy was then sucked up into the pipette and withdrawn. The glass became very soft at the higher teniperatures if left long in the alloy, but by carrying out the operation rapidly this iiiethod of extraction mas possible even a t the melting point of silver. The samples of alloy were in the shape of thin rods of a very con- venient form for examination. A portion of each sample was weighed, dissolved in nitric acid, and its content of silver estimated by ammonium thiocyanate solution which had been carefully standardised on the same silrer as that used in the experiments.The graduated instruments employed had been tested !p. 422).CONTAINIXG ZINC AXD ANOTHER METAL. 407 0 4 'TS 9 . l 5 > > by the Berlin physikalishe Anstalt, and t,he control analyses agreed, as a rule, to within very nearly 1 in 1000. The percentage of zinc was obtained by subtracting that of silver from 100. It is obvious that this method ceases to be satisfactory when the percentage of zinc is a small one ; hence the first result of Series 11 (p. 412) is not more trustworthy than that of Series 9 (p. 410). 0 419'7 2 '06 430.4 5 . i 6 497'6" 1 9 429.S TABLE IXA.SILVER ADDED TO ZINC. Xeries 1. 300 gmnas of Zim. Percentage of silver present. Atomic percentage of silver. 0 0'164 0.328 1-14 1 ' 9 4 3.50 0 0 '1 0 '2 0.7 1'19 2'15 Freezing point centigrade. 418'8 419.23 419.64 421 '9" 424.35 42970 The silver used in this series was prepared by Stas' method. * A t this stage, the alloy was heated more than 100" above the freezing point of eiiic, iii order t o bring the silver into solntion. At the recorded temperature, n precipitate began to form, and at the elid of 5 minutes, the teiiiperature haviiig fallen less than a degree, almost the whole mass had beeonie solid from the bottom upwards. In plotting this series, we have added 0.S' to all the freezing points to iiittke the freezing point of zinc the same as in Series 2 and 3.408 HEYCOCK AND NEVILLE : THE FREEZING POISTS O F ALLOYS Percentage of silver present.Atomic percentnge of silver. Freezing point centigrade. 0 4'11 7 .b's 8 *'5'0 0 2.53 4 *;2 5*;3 419-6 441*On 430'4-1- 478-7 430'41 495.2 3 430-0 538.3 (1 429.1 TT I * Here the rate of cooling became twice as slow. -k Here the rate of cooling became three times as slow, and a precipitate began to form. After a fall of two or three degrees below this point, the alloy was a solid mass. The period of constant temperature at the freezing point is not so prolonged as in the case of eutectic poiqits. $ The alloy becomes a thick paste before this point is reached, but a t this point the rate of cooling becomes three or four times as slow as immediately before, to quicken again after the freezing point of zinc is reached.5 The mass soon gets pasty after this point. 11 Here the rate of cooling became for a few degrees twice as slow as before, but i t gradually became quicker, and attained its previous rate before the lower point was reached. TI Here the halt in the cooling, though well marked, was more fugitive than with solutions containing less silver. Towards the end of this series, we began to notice some oxidation Qf the zinc. Xeries 4. 120 grums of Zinc. 19-82 24.84 13'04 16.71 571 -3" 593.9 * This is a well-marked point, the rate of cooling becoming nearly three times as After the freezing point, stirring soon becomes impossible. All the silver seems to dissolve below 600°, and at this temperature slow as before the point.carbon appears to reduce the zinc oxide. Sepies 5. #due?- added to Zinc. This series was commenced by melting together 120 grams of zinc and 40 grams of silver. After taking the freezing point, more silver was added, the total weight of silver present being recorded in column 1. At the end of the series, the percentage of silver in the alloy wasCONTAINlNG ZINC AND ANOTHER METAL. 409 3 l 2 1 found by analysis to be 37.65 per cent. This corresponds to 26.83 atomic per cents. If we assume, what is very nearly true, that no silver was lost during the experiments, we can, from the result of the final analysis, calculate the weight of zinc left in the alloy, it is 115.9 grams. Thus 4.1 grams of zinc have been lost by oxidation during the experiments. This loss distributed equally over the four experiments gives us column 2, the probable weight of zinc present at the moment of reading each freezing point.4 5 Weight of silver present. Percentage of , e ~ ~ ~ of Freezing point centigrade. silver. weight of silver. present. , 40 50 60 70 118.97 117.95 116'92 115'90 25.16 16.95 592*3* 29.77 20.47 6 o a v 33 '92 23-75 619.5" 37-65 26 *83 626.Sj. * A11 well-marked freezing points. t Here the alloy sets to a solid mass a t a temperature but little below the freezing point. Seyies 6. Silver udded to Zinc. One hundred and fifty grams of zinc and 42.02 grams of silver were melted together, and additional quantities of silver added before each reading of the freezing point. The composition of the alloy mas determined by extracting a sample im- mediately before each freezing and determining the percentage of silver, I I 1 2 3 Percentage of silver present.Atomic percentage of silver. Freezing point centigrade. 22'16 25.88 34'19 37'27 39'76 41 '80 46*73 14.73 19.77 23'97 26.50 28.59 30.36 34-74 580.9 606.0 620 -4 626'4 630.0 636-1 654*4* I I * Less than a degree below the freezing point, stirring becomes impossible on account of the abundance of precipitate, but in this and the three preceding experi- ments the alloy is very fluid at the freezing point. All the points in this series were well-marked, steady temperatures.410 HEYCOCK AND NEVILLE : THE FREEZING POISTS OF ALLOYS 1 2 3 Percentage of silver presen t. Atomic percentage of silver. Freezing point centigrade. 45'15 43.72 42'17 40'69 33'31 32.03 30.67 39-39 649 *5 644.5 638'1 6312 After the last reading, and without re-melting, w e extracted some of the still liquid alloy and found in i t 40.39 per cent,, that is, 29.13 atomic per cents.of silver. Se&s 8. This series was carried out in the same way as Series V., beginning with 100 grams of zinc and 70 grams of silver. The analysis of the alloy at the termination of the series showed that it contained 64.37 per cents. of silver, Hence, assuming no loss of silver, me find a loss of 14.21 grams of zinc. Distributing this loss equally over the experiments, we are able to obtain column 3 and to complete the table, SiZz'ei* nclclerl to Zinc. 1 Weight of silver present. ?O 80 90 100 115 130 155 4 Probable weight of zinc present. 97.97 95'94 93 '91 91'88 89'85 87'82 85'79 3 Percentage of silver by weight.41.68 45.47 48 '94 52.12 56.14 59.68 64-38 4 Atomic percentage of silver. 30.25 33.60 36-77 39.78 43.72 47'33 52.30 5 Freezing poia t centigrade. 635.8 649.7 6583 666'4 679.8 688.3 697.4 Ses-ies 9. 500 gmm of Siiz;ei*. On each occasion when the zinc was dropped into the molten silver a little zinc was seen t o volatilise and burn, but after the molten alloyCONTAINING ZINC AKD ANOTHER JIETAL. 417. had been stirred, no further burning of zinc was noticed while the solution was dilute in zinc, We thought that there was a more rapid and irregular loss of zinc during the latter part of the series. From thig cause, or foil some other reason, the freezing points of this series deduced from the weights of metal used do not lie on a smooth curve.This might be due to a real singularity in the curve, but as the first five points of this series agree very well with Series 10, whilst the later points do not, we are disposed to think that after 21.9 atomic pw cents. of zinc there is an experimental error in Series 9, probably due to irregular and more rapid burning of zinc. VVe, therefore, only use in clrawing the curve the first five points of Series 9, and the last point which, being based on an analysis, is trustworthy. This analysis might be used to correct the weight of zinc present a t tho previous readings, as was done in Series 5 and 8, but owing probably to the irregular rate a t which the zinc was lost, this method of correction does not improve matters.I n column 1 we give the nominal weights of zinc in the crucible, assuming no loss. These are, of course, all greater than the true weights, and therefore a curve plotted from them must lie above t'he true curve. The true weight of zinc present a t the last reacting was 120.35, and it is from this number that the last percentage of zinc is calculated. Total weight of zinc present. 0 6 -13 11.22 22'88 34.05 50.202 57.72 1 65-62? 78 *52 '? 92.672 107.87 Z 132*07? Percentage weight of zinc. 0 2.97 5-31 10.27 14.55 23.06 22.40 24.70 25'19 31.66 35'04 37-57:: Atomic percentage of zinc. 0 4.81 15'86 21.90 29% 32 '2 35 '1 39 '3 43.3 47'06 49.79: a 4 6 Preezing point centigrxcic. 958'9 926.9 900.7 s49 '1 508.6 763 -9 7 8 0 *9 734'5 711.1 z0673-k 103.0 695'7: * A soft precipitate was noticed some little time before the freezing point mas .t.il very steady temperature. $ The composition determined by analysis. read, and this point became here a steadier temperature thau with less zinc. Swies 10. Zinc nddecl to X i l v e ~ . This series contains a number of points deteiw~iizetl by analysis and marked A in the fourth column of the table, and also a nnmber of points for which the percentage composition is cowectetl by the following412 HEYCOCK AND NEVILLE : TEIE FREEZING POINTS OF ALLOYS analysis as in Series 5 and 7. Each sample taken out of the crucible for analysis was weighed, and hence, assuming that there mas no accidental loss of silver, we mere able to form column 1 of the table, the weight of silver present at each reading of a freezing point.Column 2 gives the weight of zinc added to or taken from the crucible immediately before each reading. Column 3 gives the weight of zinc present, deduced from analysis 01- corrected by analysis. Column 4 gives the percentage by weight of zinc, and column 5 the atomic percentage. Column 6 gives the freezing point. 1. Weight of silver present. 2. XTeigh t of zinc added before each :xperimen t. 0 + 48-51 + 9-45 - 3‘46 + 7’57 + 8’60 + 6‘75 + 10% .- 8‘32 + 10’94 + 14-72 + 15.72 + 23.65 + 20’15 + 23.65 + 31.10 - 13.05 - 12.61 - 40.05 ~ 3. Weight o C zinc present zorrected by analysis. 0 47.51 55.93 52-52 58’53 65-57 70.76 80.06 71-74 80 5 4 93.12 106’7 93’65 115’41 133.67 121.06 142‘82 102.77 132.43 ~~ 4. Percentage of zinc by weight. 0 19-20 2 1 .8 7 ~ 23’*+9 25’91 27‘40 29.9211 32’*i1 35-66 3 8 . 8 4 ~ 43’bO 47 ‘55 ti 51%9 A 57:;5a Atomic percentage of zinc. 0 28’14 31-57 36.56 38.35 41.31 33’47 44:i4 47’74 51-15 56’.b3 59’90 6 3 ’ h 69’-i2 Seyies 11. Zinc added to 200 grams of Silver. 6. Freezing point centigrade. 959.2 764.0 742.0 745.1 728-1 711.6 707.6 705.1 705.8 702’2 697-5 691-2 692 ‘8 679.S 667-5 669.3 657.2 636.5 658‘.0 I n the Fletcher blast furnace with coal-gas burning over the surface of the metal. The composition of the alloy was determined immediately before each reading by extracting a few grams with a Jena glass pipette, and estimating the silver with ammonium thiocyanate.CONTAINING ZINC AND ANOTHER METAL. 413 Percentage of zinc by weight. 0 1 '9-1 4.77 7.39 12.13 14-06 1 7 *23 17'86 19.72 22.57 1 , 24YE 24'?39 ,, Atomic percentage of zinc.0 3-16 7'63 11.62 18-54 21 '24 25-55 26-36 28.82 32.46 9 9 Freezing point centigrade. 957'6 936.8 904.0 872.3 822 +O 805.9 778.5 z69.2 455'6 733'3 * (705'6)T (705.5) 723.2 (705.5) 717.9 (705 '4) (705 '6) 711'3 (705.8) 705 '6 Atomic fall. 6.58 7.02 7 '34 7 *32 7.15 7 *01 7-15 * This temperature was known to be a little too low at the time of reading. -t. This and the other numbers in brackets are eutectic freezing points, below the first freezing point, and correspond to the moment when that part of the alloy which is still liquid has, through the separation of solid silver, reached the compositioii of 37'5 atomic per cents. of zinc. These freezing points, especially the last tTo, were very cons tan t temperatures.The table, as always, gives the observed freezing points, but in drawing the curve we shall add 1.4"C. t o each one in order to make the freezing point of silver 959"C., as in Series 9 and 10. Xeyies 12. Zinc added to Silver. Conditions similar t o Series 11, composition of alloys found by analysis. Percentage weight of zinc. 41 '65 42.72 44'68 46 '76 47-48 52.40 56.63 57-68 59'21 60'70 Y , Atoinic percentage of zinc. 54.06 55.14 57 '1 1 59 '16 69'84 64.45 68.28 69'13 70.52 71.80 9 , 684'8 682.3 676.6 670.6 667'9 655'4 643.0 636'4 (some indications of R 637.9 very steady. d30.6 ditto. 628'8 stop here).414 HEYCOCK AND NEVILLE : THE FREEZING POINTS OF ALLOYS The Ziiws2ce.r. Czwve. This curve (Figs. 13, 14, 15, p. 422) presents several peculiarities ; indeed, it is the most remarkable curve we have as yet examined.From pure silver to 37.5 atomic per cents. of zinc, the experiments allow us to dram it as very nearly a straight line ; there is a per- ceptible upward concavity after 20 atoms of zinc, but it is very slight,. We are not quite certain, however, that a minute cryoscopic examina- tion of this part of the curve might not reveal further details in it. At 37.5 atomic per cents. of zinc, there is an abrupt angle, and the curve becomes for a short time nearly horizontal, the depression produced by the next few atomic per cents. of zinc being very slight; but the slope slowly increases so that the curve, while always tending downwards, is convex. Near 61 atomic per cents. of zinc there is an obtuse angle, and from this point another, but shorter, convex branch proceeds, end- ing in a somewhat more pronounced obtuse angle a t 70.5 atomic per cents.of zinc. From this last angle, the curve, always convex, sweeps downwards with increasing steepness to near 98 atomic per cents. of zinc, where mother obtuse angle occurs. From this angle down to the melting point of zinc, we have drawn it as a straight Iine, though there ate perhaps hardly enough experimental points to justify us in doing so. Figure 14 shows an independent series of experiments, carried out in order to confirm the two middle angles. The points of this series are not plotted on the main curve, but are shifted 25' lower down, SO as to distinguish them from the others. It will be seen that Fig.14 completely confirms the accuracy of the main figure, putting the position of the angle a t 70.5 atoms beyond question. Unfortu- nately, no experiments were made between 60 and 63 atoms, so that the angle near 61 atoms, though both figures show its existence, is not so accurately located. The curve above described is that of the first freezing points of each alloy, recording the temperature a t which the alloy begins to pre- cipitate solid matter. Our figures also show that second freezing points mere detected between 32-5 and 36.5 atomic per cents. of zinc. These second freezing points are identical with the first freezing point of the alloy containing 37.5 atomic per cents. of zinc. Each of these was a very constant temperature lasting for a long time without change, so that a large amount of solid matter must form here without change in the composition of the residual liquid.Probably more of these points still further to the left could have been found had they been looked for. These second freezing points occurring long after the first f. p., indicate the moment when, through the separation of matter richer in silver than the liquid, the still liquid part of each alloy attains the coniposition of 37.5 atomic per cents. of zinc. We looked for such second freezing points to the left of the angles a t 61 andCOXT~~INI8"G ZINC AKD ANOTHER METAL. 415 70.5 atomic per cents. of zin2, but, with one doubtful exception, ~ v e failed to find any. From 90 to 98 atomic per cents. of zinc, a mell-marked horizontal row of second freezing points is seen.A good deal of solid matter separates before the temperature falls t o the level of these second freezing points, but they are well-marked, very stationary tempera- tures, becoming steadier and steadier with each addition of zinc. They are hardly so steady as a eutectic point, but a degree or two below them the alloy sets t o a solid mass. The first f. p. differs a good deal in character at different parts of the curve. That of pure silver is a very constant temperature, but when a few per cents. of zinc have been added, it is much more fugitive. At about 32 atomic per cents. of zinc, we noticed that the period of constant temperature at the f. p. became longer. On the almost horizontal portions of the curve which occur immediately t o the right of each of the first three angles, there is a prolonged halt in the cooling at the f.p. For example, a t 65.3 atoms of zinc the alloy appeared to solidify a t a constant temperatnre, and at 73.2 atoms it mas noticed that the alloy set t o a hard mass a t or very near the f. p. At 70.5 atoms of zinc, the f. p. was very steady, and a t 40 atoms the period of constant temperature a t the f. p. was prolonged. It is clear that, wherever we see the curve to be nearly horizontal, we can predict that the freezing point will be marked by a very steady temperature, for much solid matter must form before the composition of the liquid can alter sufficiently to change the f. p. perceptibly. The converse is not, however, true, for between 98 and 100 atoms of zinc the freezing point curve is a line sloping rapidly downwards, whilst each freezing point is an absolutely constant temperature at which the whole alloy solidi- fies.We noticed it peculiarity similar t o this in the freezing points of cadmium containing tt little silver. From 80 to 98 atoms of zinc, the upper freezing point is very fugitive, and it is clear th3t very little soiid matter is formed a t the f. p. Description of the SiZp;ei*-xirzc Alloys. The samples of alloy extracted for analysis were broken by repeated bending, or, when necessary, by hammering. We thus obtained a rough estimate of the degree of toughness or brittleness of the speci- men, and were able t o examine the fractured surface with a lens, There was also sometimes a free surface where the alloy had solidified in contact with the air.It is known that the information that can be gained from such an examination is very complicated and much affected by the rates at which the metal has cooled, but a few features struck US as worth recording. From pure silver to 34.3 atomic per cents. of zinc, the alloy is fairly416 HEPCOCK AND NEVILLE : THE FREEZING POINTS OF ALLOYS malleable, requiring to be bent to and fro a good many times before it, breaks, but at 35.3 atoms it is much more brittle, still more so at 36.5, still brittle at 37.7, but at 41.3 it has become tough. At 51.15 it is highly brittle, scarcely bending at all, in fact, becoming still more brittle up t o 60 atomic per cents. of zinc, when it crushes like glass. It is still brittle at 64.18, but a t 69.5 it is quite tough, and this tough- ness, while diminishing somewhat, is present up to 72 atoms of zinc.I n other words, with the curve before us we may say that the alloy is malleable or tough up to near the first angle, but that a, few per cents. before and up to the angle it becomes brittle. Its character im- mediately after the angle, we do not know, but at 41.3 it is malleable and tough, thence it gradually becomes more brittle, until a maximum of brittleness is reached at 60, just before the second angle. The brittleness persists, though not so markedIy, until near the third angle, but close before this, at 69.5, it is not at all brittle and, as far as we have examined, there is some toughness. The fractured surfaces were finely grained a t first, but a t 18.5 atoms of zinc there was a trace of conchoidal fracture. From 25.5 atoms almost up to the angle, most of the alloys showed on t'he fractured sur- face, and on any free surface, dendritic crystals, the minor leaflets standing out like the teeth of a comb a t right angles to a central rib.At 31.6 atoms of zinc, the whole fracture consisted of such crystals in very high relief. Beyond the first angle, we found no trace of these crys t als. Close t o the first angle, at 37.7, the fracture showed an irregular pitted surface, at 41.3 the grain is much finer. At 51.15, the alloy breaks as if the larger units of structure were polyhedra with plane faces a millimetre or more in size. Each of these faces is minutely pitted. Another portion of thisalloy, when broken with a hammer, showed red crystals in a cavity." This alloy does not give one the im- pression of being homogeneous.At 54 atoms of zinc,the fracture is rock- like, or perhaps more like that of galena, From 59 to 63 atoms, all the alloys me examined had a conchoidal fracture with a brilliant glassy surface, no texture or crystals were visible, and the alloy seemed to be perfectly homogeneous. This is the region of the alloys that are as brittle as glass. At 64.5 atoms of zinc, the conchoidal fracture has quite disappeared, and the fractured surface consists of a confused mass of minute, short, crystal faces. From here up to 69 atoms, the fracture gets coarser and is like cast iron, but just beyond the angle, at 70.5, the conchoidal fracture shows itself again, not, however, so strikingly as at * Alloys whose composition is near t h a t indicated by the formula AgZn, although under ordinary circuptances of a silver white colorrr, become externally bright red when heated to 300" and suddenly cooled.We have discussed this phenomenon in a paper read before the Cambridge Pliilosophical Society in November, 1896.CONTAINING ZINC AND ANOTHER METAL. 417 the previous angle. with higher percentages of zinc. We have not examined in this manner the alloys Discussion of the i*esuZts. While certain features in this remarkable curve need further ex- periment before they can be satisfactorily explained, we can arrive at some conclusions from the facts already ascertained. There can be no doubt that the angles a t 61 and 70.5 atomic per cents.of zinc indicate the existence of a t least two chemical compounds of zinc and silver. But the formulae of these compounds appear to us very uncertain. The angles show that they are not wholly dissociated into their constituent metals at the melting point of the alloy, but that they are, to a large extent, so decomposed is rendered probable by the absence of eutectic minimum freezing points at the two angles, and by the continual down- ward trend of the curve, which nowhere shows a maximum freezing point. If the compounds were quite stable a t the temperatures at which the alloy melts, a maximum freezing point, or intermediate summit, would occur in each convex branchof the curve, and the com- position of the alloy a t this summit mould tell us the formula of the compound.But the partial dissociation of the alloy degrades the summit, so that itsbecomes difficult to locate it, although it mill probably not shift its position to right or left.” We must, therefore, abandon the hope of reading with certainty from the curve the forivulae of the chemical compounds that the metals can form; although it is obvious that such formulae as Ag,Zn,, AgZn, Ag,Zn3, AgZn,, Ag,Zn,, AgZn,, are fairly consistent with what we as yet know. I n previous papers, we have more than once expressed the opinion that most chemical com- pounds which metals form with each other dissociate to a very large extent on melting, and the more cases we study the more convinced we are that this is the case.? The microscopical study of the alloys and the determination of the points on the curve a t which the alloy solidifies homogeneously may help us to fix the formulae of the compounds.The first of these two investigations, we have not yet had time to attack, but should it appear that others are not engaged on it, we hope to attempt it. The some- what cursory examination of the alloys already made shows that near and on both sides of the angle a t 61 atoms of zinc the alloy is strikingly homogeneous, and that this is also the case immediately to the right of the angle a t 70.5 atoms. The conchoidal fracture is similar at these two points and absent elsewhere. I n fact, without having seen the curve one could, from the physical properties of the alloys, pick out * See Heycock and Keville, “The Freezing Points of TriiJe Alloys,” Trans., 1894, 65, p.70. + See also Foerster, ,~rutzirwissenschuftliche Rzcndsschnzc, 3 894.418 HEYCOCIC AND KEVILLE : THE FREEZIKG POINTS OF ALLOYS these two points as similar and specially remarkable. The period of constant temperature a t the freezing point is also very prolonged here, But all these features can be explained in a t least two ways,-either the angles are eutectic points, in which case the alloy solidifying, though not a chemical compound, is necessarily very homogeneous, or else, in opposition to the simpler theory of the freezing point curve, they cor- respond to chemical compounds. Assuming dissociation, the occurrence of an angle at the formula of a compound that really exists in the solid state does not contradict the theory.The fact that an alloy appears to solidify at a constant temperature may be due to one of several causes. 1. The liquid alloy may consist of two conjugate liquids, as in the case of zinc-bismuth. We are not at all sure that the first angle at 37.5, together with the flat to the right of it, may not be due t o this cause. 2. The alloy may be an ordinary eutectic alloy, or, to speak more generally, the solid forming may consist of two conjugate solids. These two cases may be brought under one heading, but with this difference, that in case (1) the eutectic alloy occurs above the melting point of the more fusible metal, while in case (2) it occurs a t or below this melting point. 3. The solid forming may be a definite compoundof the same coru- position as the liquid from which it is separating.This may ba the explanation of the steady temperatures at 61 and 70.5 atoms of zinc. We should expect this to ha,ppen a t a summit corresponding to a stable compound, but we have not yet found such a case; gold-aluminium and some other aluminium alloys would very probably afEord instances of this. 4. The two substances present in the liquid alloy may be solidifying isoinorphously in the same proportion as that in which they are present in the liquid. It has occurred to us that the short line, from 100 to 98 atomic per cents. o€ zinc, which, if produced, passes nearly through the f. p. of pure silver, may indicate that, in this region, the zinc and silver are separating isomorphously. But this point, like the similar cases of zinc-gold and zinc-copper, is one that needs further investiga- tion.I t may be that the isomorphism is not between zinc and silver, but between zinc and a compound of silver and zinc. I n the very similar case of dilute solutions of silver in cadmium, we found that the solid separating at first contained more silver than the mother liquid. This rather points to the probability that the substance separating between 100 and 98 atoms of zinc is a solid solution, in which case, as Van’t HOE has pointed out, the straight line of freezing points would prove that Henry’s law holds good between the concentrations in the solid and the liquid phases.CONTAINIKG ZINC AND ANOTHER METAL. 419 TABLE X. Gold added to Zim. In a Fletcher draught furnace, in a cylindrical clay crucible imbedded in a larger Salamander crucible, the space between being filled with broken fragments of crucible. Coal gas burning over the surEace of the metal.Hand-stir with clay ring stirrer. 250 gmms of Zinc. Percentage weight of gola. 0 0.296 0.903 4.08 5 '94 9.40 13.G6 1 s'.'16 9 , Atomic percentage of gold. 0 0.09s 0.302 1.374 2.054 3'33 4'754 7 7 s'.'olS Freezing point centigrade. 418*i9 419.29 419'03 423'50* 425.81 4 3 0 ' 0 0 ~ 431.75: 432.27 431'65 461'34 431.42g 46 2 '26 I 431717 * KO precipitate was noticed a t the moment d i e n the f. p. was read, and the lioL!nid seemed very fluid, bnt after this, a t the ~ccnie ten~perntzwe, the alloy becomes solid. -t. Ka precipitate was noticed for some time after reading the f. p., hut filially a precipitate formed while the stirring was still easy. The f.p. is still well-marl;ed here, but not 60 constant as with less gold. $ Also niarked decrease in rate of cooling a t 444.13", another time a t 444.71". $ Marked decrease i n rate of cooling aceonipanied by forniation of precipitate a t KO precipitate could be detected at the point here recorded, but soon after it 461.8" foxned freely and the whole mass became pasty, so that stirring was impossible. "T; A very steady temperature, The gold was dropped into the liquid zinc in these experiments. KO incandescence mas noticed when the gold was dropped in. -4s in the similar cases withsilver and copper, there is, at the freez- ing point below the first flat, not merely a temporary halt in the cooling, but the whole mass appears to solidify a t or near the recorded temperature. TABLE XI.Coppel. nddetl t o Em. h'wies 1. The conditions were the same as in the gold-zinc experiments, The first quantity of copper was added as an alloy, but Table X. nftermards the copper was dropped into the molten zinc.420 HEYCOCK AKD NEVILLE : THE FREEZING POINTS OF ALLOYS 0 5,846 3 , 11 *'65 15 'f0 Percentage weight of copper. 418'93 423 '58 * 423'55 524'88 422'4 ? 695'8 :: 667.2 9 I I I Atomic percentage of copper. Freezing point centigrade. 0-134 0,364 1 '042 3'11 6 *7G 0 0-139 0-377 1.08 3'22 6-98 418'82 419.17" 419.77 421'70 423.81t 423.96:: * This f. p. is a stationary temperature for several minutes. + A considerable amount of precipitate forms even above the f. p. $ With this concentration, we thought there was a decrease in the rate of cooling at 561*6", and much precipitate had formed in the crucible a t 541 -8". Xeyies 2.Fus*nuce A . The alloys mere made by melting together, in a sealed vacuous tube of Jena glass, weighed quantities of copper with a considerable excess of zinc. When the alloy thus formed had been well melted and shaken, it mas allowed to cool, the tube opened, and the alloy added t o the remainder of the zinc in the crucible. 0 0.402 1 -838 2.590 41633 0 0.416 1 *goo 2.678 3 , 4'167 418.93 419.77 422'79 423.60" 435'36 423.5 423.61. * Very steady temperature. -t. Although this is a well-marked f. p., the alloy was pasty before the temperature fell to this point. No higher point could be detected. Xeries 3. 250 gmms of Zinc. Dyopped the copper into the zinc. I I ~ ~~~~~~~~ * At this point there was so much heavy precipitate already formed that stirring t Lower point not so well marked. 5 The point on the lower flat can no longer be detected. was impossible. A well marked f. p., triistworthy.CONTAINING ZINC AND ANOTHER METAL. 421 Zinc-Gold and Zinc-Copper. These curves have only been traced by us for comparatively dilute solutions of these metals in zinc. The completion of the gold-zinc mas deferred to a future occasion, on account of the expense of handling the considerable quantities of gold needed, that of copper partly because, when me had carried our experiments to the point given in this paper, we became aware that M. Charpy had completed the copper-zinc curve. We were also influenced by the fact that the numerous analyses that would have been necessary would have required much greater labour than was the case with the alloys containing silver. It will be seen that these curves closely reproduce the phenomena of the corresponding part of the silver curve. The first angle and flat occur at a different temperature in each case, but in all three we have, starting from pure zinc, a line of steady freezing points, which for gold was very straight. In this region, we have the Bame phenomenon of almost complete solidification without further fall in temperature when the f. p. has been reached, Just before 2 atoms of copper or 4 atoms of gold, we have a very similar angle, and then the very fugitive upper freezing point, followed by copious precipitation, and, a t a con- stant lower temperature, the steady lower freezing point. I n the case of copper, we found that as we progressed to the left, by adding copper, this lower freezing point on the flat became less marked and finally before 16 atomic per cents. was lost. This is a reason f o r believing that the matter precipitating between the two freezing points was not pure copper, although it clearly contained more copper than the liquid in which it was forming. It is evident that, when- ever the explanation of the silver-zinc curve is found, that of the other two will follow. Zinc- Pkatinum. We do not give a table for this pair of metals, but we have made R few experiments on addingplatinum to molten zinc. I n some cases, the alloys were made in sealed glass tubes, in other cases the platinum was dropped into the molten zinc. Nearly four per cent. of platinum by weight was added in portions to the zinc. It appears to dis- solve readily, but it does not appreciably alter the freezing point of the zinc. Each f. p. was a very constant temperature, stirring becoming impossible before the pyrometer indicated any fall. It has occurred to us that the flat of the previous cases may here be at the f. p. of zinc, and that the upper freezing points may have been so high or so fugitive, that we failed to detect them. We hope t o ex- amine this point again. The experiments described in this paper were, to a large extent, carried out by means of apparatus purchased by funds supplied to us VOL. LXXI. G G422 FRANCIS : THE DI-NITROSAMINES OF ETHYLENEANILINE, by the Grant Committee of the Royal Society. We wish, also, t o thank Miss Dorothy Marshall, B.Sc., for the efficient aid we received from her in many of the experiments.HEYCOOK AND NEVILLE. Jozcrn. Chem. SOC., April, 1897. A ZINC A u o ~ s . - Fig. 13. The complete curve, Fig. 14. Series XII. drawn 25" Lower, but on the same scale.

ISSN:0368-1645    

DOI:10.1039/CT8977100383

出版商:RSC    

年代:1897

数据来源: RSC

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422 FRANCIS : THE DI-NITROSAMINES OF ETHYLENEANILINE, X L. - The Di-nitrosamines o j E t h y leneaniline, the Ethylenetoluidines, and their Derivatives. By FRANCIS E. FRANCIS, Ph.D., B.Sc., Lecturer in Chemistry, University College, Bristol. 0. FISCHER and E. HEPP (Be?*., 1886, 19, 2992 ; Bey., 1887, 20, 1247, &c.) have shown that the aromatic nitrosamines, on treatment with alcoholic hydrochloric acid, yield paranitroso-derivatives. Thus nitroso- methylaniline, C,H,*N*CH,*NO, gives paranitrosomethylaniline hydro- chloride, NO*C,H,*NH* CH,,HCl. Should the para-position be already occupied, then, in the benzene derivatives, either no action takes place or the nitroso-group is removed, whereas in the naphthalene series the nitroso-group enters the ring in the ortho-position relatively to the substituted nitrogen atom.It was thought of interest to try whether similar changes took place in di-nitrosamines, and for this purpose those of ethyleneaniline and the ethylenetoluidines mere investigated. It was found that the molecular change is best brought about by a mixture of glacial acetic and concentrated hydrochloric acids, molecular rearrangement taking place rapidly and, if care be taken, the yields are good. If the para- position is occupied by a methyl group, decomposition occurs when the same treatment is adopted; the oiily substance capable of isolation is ethyleneparatoluidine, the nitroso-groups being removed. On the other hand, if the substitution is in the ortho- or meta-position, the molecular change takes place in the normal way.Tlie dinitroso-derivatives are easily reduced to the corresponding dianiines, that obtained from dini- trosoethyleneaniline yielding quinone on oxidation with potassium dichromate, showing that these substances are diamines of the type of ethyleneparaphenylenediamine. They give salts with 4HC1 corres- ponding to ethylenemetaphenylenediamine and ethyleneparamethyl- metaphenylenediamine prepared by Gattermann (Bey., 1884, 1’7, 779). They are very readily decomposed by nitrous acid, and give characteristic colorations with ferric chloride, They do not react with ketones, but readily condense with aldehydes, one molecule of the base acting on two of aldehyde.THE ETHYLENETOLUIDINES, AND THETR DERIVATIVES. 4% I. PaP.cccliniti.osoethyZe~ectniZine Hyclrochloi-itle, NO*CGH,.NH*C,H,.NH.C'GH,*N0,2HC1.This compound is prepared from the dinitrosamine of ethylene- aniline, C,H,[N(NO)-C,H,],, by dissolving it in about 5-6 times its weight of glacial acetic acid, adding half the volume of concentrated hydrochloric acid, and keeping at 60" with continual shaking for about ona hour. The nitrosamine, which separates out at first, gradually dissolves, and, on standing, the hydrochloride of the paradinitroso- derivative crystallises out almost completely. It forms a yellowish- brown, microcrystalline powder, which dissolves in water giving an intense yellow solution ; it is slightly soluble in alcohol and hot acetic acid, but insoluble in ether or benzene. The free base prepared from the salt is an orange-brown powder only very slightly soluble in the ordinary solvents.The following results were obtained on analysis. Found. Calculated. N = 15.93 16.32 per cent. HC1 = 20.84 21.28 ,, Et?yZenedipheny Zenepc~rccteti.ccmine, C,H,( NH C,H,* NH,),. Ten grams of the corresponding nitroso-derivative were reduced with excess of stannous chloride in concentrated hydrochloric acid. The tin double salt of the reduced substance separated out after each addition of the nitroso-compound to the cold solution ; this mas filtered off, and a solution of it in water decomnosd while hot with a slight ex- cess of potash solution ; on cooling, 4 grams of the substance separated in glittering plates. It is best recrystallised from water containing some potash, otherwise it rapidly becomes coloured. The melting point is 150".It is only slightly soluble in the ordinary solvents. Oxidised in the usual way with potassium dichromate, it gives a good yield of quinone (m. p. = 116"). The following results were obtained on analysis. C H N Found ......... 69-09 7.57 23.21 per cent,. Calculated ...... 69.42 7 4 3 23.14 ,, E t ~ y Z e l z e d i ~ l ~ n ~ Z e ~ p a i . ~ t e t r c L e Hyd~oc7~Zo~icle, NH,. C,H,*NH* C,H,*NH- C6H,,4HC1. When the base is dissolved in boiling water and excess of hydro- chloric acid added, the hydrochloride crystallises out in glittering plates on cooling. It is very soluble in water, but insoluble in hydro- chloric acid. Its solution is coloured intense blood-redwith ferric chloride, and dark red with potassium nitrite, decomposition taking place imme- G G 2424 FRANCIS : THE Df-NITROSAMINES OF ETBYLENEANILINE, diately even a t 0'.The same result is obtained using amylic nitrite and an alcoholic solution of the hydrochloride, but no cry stallisable pro- ducts could be isolated from the solution. Platinic chloride is partially reduced, and it was not found possible to isolate the double salt, even at low temperatures. A solution of the hydrochloride poured into a hot, strong solution of stannous chloride gives characteristic glittering prisms of the tin double salt on cooling. Found. Calculated. HC1 = 37.88 37-63 per cent. Ethylenetetracety Zdip~e~ay/enep6c?.c~tetrami~e, C,H,O *NH* C,H,*N( C,H,O)* C,H,*N(C2H,0)*C,H,*NH* C,H,O. On heating the ethyleneparaphenylen ediamine base with excess of acetic anhydride for some hours, the tetracetyl derivative is formed ; this can be isolated by neutralising the diluted solution with potash, when it is precipitated as a greyish, crysta,lline powder which may be recrystallised from nitrobenzene.It is insoluble in the ordi- nary solvents, but soluble in dilute acids. I t s melting point lies above 290". The following results were obtained on analysis. Found. Calculated. C = 64.06 64.39 per cent. H = 6.41 6-34 ,, Ethy ZenedibenxgZidenecliphenyZeneparatetrarnine, C,H,* CH :N* C,H,*NH C,H,- NH*C,H, N: C H*C,H,. When ethyleneparaphenylenediamine is warmed in benzene or alco- holic solution with benzaldehyde, action takes place immediately. I n alcohol, a yellowish powder is thrown down, which may be recrystallised from hot benzene, and is obtained in the form of pale yellow, silky needles melting a t 226-227'.It is very soluble in chloroform, only slightly so in boiling alcohol, and insoluble in ether or water. Warmed with dilute hydrochloric acid, it immediately takes up water, the base and benzaldehyde being regenerated. If it is suspended in alcohol, and alcoholic hydrochloric acid added, the solution becomes red, and an unstable hydrochloride is deposited ; this decomposes on warming, and cannot be isolated. Found. Calculated. N = 13.38 13.40 per cent. EthgZenedisa Zic ylidenecliplmy Zezneparcctetrarniw,e, OH C,H,*CH :N* C,H,'N H*C,H,*N H C,H,*N : CH* C,H,* OH. The action of salicylaldehyde on ethyleneparaphenylenediamine takes It is bed recrystal- place on warming the two in alcoholic solution.THE ET HPLENETOLUI DINES, AND THEIR DERIVATIVES.425 lised froin warm nitrobenzene, when it is obtained as small, orange- yellow plates melting at 224". It is but slightly soluble in alcohol, benzene, or chloroform, insoluble in ether or water, readily decomposed by dilute hydrochloric acid, and, like the benzaldehyde componnd, gives an unstable hydrochloride with alcoholic hydrochloric acid. Found. Calcnlated. c! = 74.37 74.66 per cent. H = 5.91 5-77 ,, 11. Diniti*osanz.ine of Etl~?lZe~zeoi'thotoZzcidine, C,H,[N(NO) 9 C,'H,* OH,],. Ten grams of ethyleneorthotolizidine are dissolved in alcohol, excess of hydrochloric acid added, and then sufficient acetic acid to keep all the hydrochloride in solution; on adding the requisite amount of nitrite to the ice-cold solution, the nitrosamine separates out as an oil which slowly solidifies.It can only be obtained pure with the greatest diffi- culty, as it is very soluble in all organic solvents. A small portion re- crystallised from dilute acetone, and afterwards washed with absolnte ether, gave a pale yellow, crystalline mass, melting between 94" and 95". The following nitrogen determination showed that it was not quite pure. Found. Calcnla tcd. N = 18.28 18.78 per cent. ~tl~ylenepa~.adinitro~o~.t~otolzcie Hydv-ochloyide, NO-C6H3(CH3)*NH* C,H,*NH* C6H,(CH,)*N0,2H01. Five grams of the above dinitrosamine were dissolved in 25 C.C. of glacial acetic acid, and 10 C.C. of concentrated hydrochloric added; on standing in a warm place for a few hours, 5 grams of the hydrochloride of the dinitroso-derivative separated as a greenish-yellow, crystalline powder which darkened on drying.It is soluble in water and alcohol, but insoluble in ether or benzene. Found. Calculated. HC1 = 19.44 19.67 per cent. Bt7~yle.ne~~o~~tl~otoZ~yle1ae~c,a~~atet~rcmine Hydrocldoi*ide, NH,* C,H,(CH,)*NH* C,H,* NH- C,H,( CH3)*NH,,4HCl. When the dinitroso-derivative is reduced with stannous chloride in concentrated hydrochloric acid, care being taken that the temperature is kept low, the tin double salt of the reduced substance separates out in crystalline masses. These are collected, dissolved in water, the solution decomposed by sulphuretted hydrogen, and the tin sulphide426 FRANCIS : THE DI-NITROSARIINES OF ETHY LENEANILINE, removed by filtration ; the filtrate containing the hydrochloride is now concentrated, and gaseous hydrogen chloride passed in until the whole of the salt has separated.It is obtained in small, glistening needles extremely soluble in water, the solution rapidly becoming intense blue on exposure to air. The solution in water gives the characteristic blood- red coloration with ferric chloride, also a red coloration and spontaneous decomposition with potassium nitrite. A solution of the salt when poured into a strong solution of stannous chloride deposits character- istic needles of the tin double salt. Alkalis precipitate the base as an oil which slowly solidifies on stmanding ; it is fairly soluble in water, ether, and alcohol. The analysis gave Found. Calculated. HC1 = 35.19 35.09 per cent.N = 13.80 13-46 ,, Ethyle nedibenxyZiclenec2ior~~Lotolzcy Zenepc~?.atetii~~i~~e, C,H,* CHIN* C,H,(CH,)*NH* C,H,*NH* C,H,(CH,)*N:CH* C,H,. If a solution of the base in alcohol is warmed for a few minutes with benzaldehyde, the condensation product is thrown down in large, yellow plates melting a t 175-176° ; it is very soluble in chloroform, slightly so in ether or alcoho1,”and can best be recrystallised from benzene and alcohol. It is decomposed by dilute acids into the base and benzalde- hyde, but forms an unstable hydrochloride in the same way as the ethyleneaniline derivative. Found. Calculated. N = 12.65 12.55 per cent. Et?LyZe.nemetutoZuidine, CH,* C,H,*NIX* C,H,*NH. C,H,* CH,. Metatoluidine and powdered sodium carbonate are heated together in an oil bath to 120Oin a flask fitted with a reflux condenser, the necessary amount of ethylenic dibromide is then added, and the whole heated for 20 minutes a t 150’ with continual shaking ; the reaction is then complete.The mass is treated with water, and the residual oil washed with dilute acetic acid to remove any metatoluidine unacted on; the product is then dissolved in twice its weight of alcohol, and after standing 3 days, the whole of the tertiary arnine, n,-dimetatolyl- piperazine, crystallises out. The hot alcoholic solution is then treated with an equal volume of concentrated hydrochloric acid, when, on cool- ing, the hydrochloride of the base separates in colourless needles ; this is insoluble in concentrated hydrochloric acid, dissociated by warm water, and can best be purified by recrystallis9tion from hot alcohol.It melts at128’. The yield is poor. The recrystallised hydrochloride gave the following figures on analysis.THE ETHYLENETOLUIDINES, AND THEIR DERIVATIVES. 42’7 Found. Calculated. HCl = 23.19 23.32 per cent. N = 8.80 s.95 ,, The free base is only obtained in the crystalline condition with con- siderable difficulty, The alcoholic solution of the salt is neutralised with alcoholic soda, and the sodium chloride formed is filtered off ; to the filtrate, a small quantity of tvat,er is first added, and then sufficient ether to dissolve the oil which separates. I n this way, flat plates slowly form, very soluble in the ordinary organic solvents, and melting at 58.5’. Found. Calculated. N = 11.50 11 -67 per cent. n-Dimetutoly~ipe~axine, CH,.c,H,*N<~~:: :::>”* c,H,* CH,. The tertiary amine formed in small quantities in the above prepara- tion crystallises from hot alcohol in flat plates melting a t 1 2 6 O , very soluble in ether, carbon, bisulphide, and benzene, but almost insoluble in cold aIcohol. Found. Calculated. N = 10.66 10.52 per cent. Dinitrosamine of Et7~yZenerr2etccto~u~~~~e, C,H,[N(NO) - C,H,* CH,],. The hydrochloride of ethylenemetatoluidine is dissolved in alcohol and treated with the necessary amount of potassium nitrite. The pro- duct crystallises in small, reddish-yellow plates, melts a t 1 1 2 O , and is very soluble in hot alcohol, almost insoluble in cold, soluble also in benzene, ether, and carbon bisulphide. Fonnd. Calculated.N = 18.90 18.78 per cent. E’thyZe~zedinzetutolu~lenepai~atet~ccnai?ze, C,H,[NH* CoH3( CH,) *NH,],. It is prepared in a similar way to the corresponding orthotoluidine derivative. The base is fairly soluble in hot water, from which it is obtained in the form of small plates on cooling. It gives a carmine-red coloration with ferric chloride, and a dark red solution and imme- diate decomposition with potassium nitrite, Platinum tetrachloride is reduced a t the ordinary temperature. It is very soluble in alcohol and hot benzene, almost insoluble in ether and carbon bisulphide, and can best be recrystallised from hot benzene or a mixture of benzene and ether. It melts a t 143’. Found. Calcul atcd. N = 20.85 20.74 per cent.428 WALKER AK’D LUMSDEN : DISSOCIATION-PRESSURE OF Biniti.osanzine of ~~l~~IenepcIratoluidine, C2H,[ (NO)N* C,jH,* CH,],, Ethyleneparatoluidine is dissolved in the necessary amount of hy- clrochloric acid, and to the cold dilute solution potassium nitrite is added ; the nitrosxmine is thrown down as a pale yellow, crystalline mass, which can best be recrystallised from chloroform and alcohol or from hot acetic acid. It melts a t 1 8 3 O , and is insoluble in alcohol and ether. Attempts mere made to reduce i t to the corresponding hydrazine, but in all cases the nitroso-groups were removed and ethyleneparatoluidine re-formed. When treated with a mixture of acetic and hydrochloric acids in the may previously described, the hydrochloride of ethylene- tolaicline was the only substance that could be isolated. Found. N = 18.82 Calcnla ted. lS.77 per cent. By the kind permission of Professor Campbell Brown, mostl of the above work mas carried out in the Research Laboratory of University College, Liverpool.

ISSN:0368-1645    

DOI:10.1039/CT8977100422

出版商:RSC    

年代:1897

数据来源: RSC