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Proceedings of the Chemical Society, Vol. 14, No. 200 |
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Proceedings of the Chemical Society, London,
Volume 14,
Issue 200,
1898,
Page 239-246
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摘要:
/88Uad 8/12/1898 PROCEEDINGS OF THE CHEMICAL SOCIETY. EDITED BY THE SECRETARIEX. No. 200. Session 1898-9. December lut, 1898. Professor Dewar, F.R.S., President, in the Chair. Certificates were read for the first time in favour of Messrs. Samuel William Allworthy, The Manor House, Antrim Road, Belfast ; John Frank Blackstraw, Holly Bank, Marton, Chelford, Cheshire ; Henry Cort Harold Carpenter, 109 Banbury Road, Oxford; Frank Cope, 30 Leeds Road, Dewsbury; Thomas James Cozens, The Grammar School, Middleton-in-Teesdale, Go. Durham ; Samuel Godfrey Hall, 19 Aberdeen Park, Highbury, N. ; Thornas Anderson Henry, 37 Chelsea Gardens, S.W. ; Thomns&uxton, 4 Cavendish Square, Nargaret Street, Hull ; James Roberts, jun., 43 Great Western Road, Glasgow ; Frederick William Skirrow, GraystongiIl, Bentham, Lancaster ; Charles Ernerique Szarasy, 19 Weymouth Street, Portland Place, W, ; Thomas Wilson Wormell, 184 Burrage Road, Plumstead, S.E.A ballot for the election of Fellows was held, and the following were subsequently declared duly elected. Hugh Poynter Bell, B.A. ;Reginald Arthur Berry ;Walter Birkett ; Thomas Henry Boardman, B.A. ;Marston Taylor Bogert, A.B., Ph.B. ; Arthur Brooke, B.A. ; Johannes Christian Briinnich ; John Paul de Castro; Charles Robert Carroll ; David Leonard Chapman, B.A. ; William Samuel Crouch ; Alfred V. Cunnington, B.A. ; W. Brown Davidson, M.A., Ph.D. ; Samuel Dickson ; Francis Alfred Drake, B.Sc. ; James Edward Ferguson ; Edward Gardner ; John Naish Goldsmith, B.Sc., Ph.D.; E. B. Hadley ; Alfred Hartridge, B.A. ; John Haworth ; Alexander Garden Hendry ; George W. F. Holroyd, B.A. ; Walter Howe ; Thomas Hill-Jones ; Benjamin Jordan-Smith ; Reginald Arundale Kay ; John Charles Mascarenhas ; William Lash Miller, B.A., Ph.D. ; Thomas Arthur Nightscales ; William Pollard, B.A., Ph.D. ;John Armstedt Ray, jun., B.A. ; Eduiund Milton Rich ; Gilbert Rigg ; Henry John Rofe, B.A. ; Henry J. S. Sand, Ph.D. ; Richard Seligman ;George Senior, B.A. ; Samuel Smiles, jun., B.Sc. ; Basil Steuart ; Ambrose Walton ; Frederick Louis Wilder ; Charles William Tuthill Woods ; John Henry Young, B.Sc. The following papers were read :-144. “The oxidation of polyhydric alcohols in presence of iron.” By Henry J.Horstman Fentoa, M.A., and Henry Jackson, B.A.,B.Sc. In continuation of the study of, the influence of ferrous iron on the oxidation of various hydroxy-compounds, the authors are engaged in investigating the behaviour of various alcohols, and the present communication gives an account of the results which, so far, have been obtained. The monhydric alcohols (methylic, eth ylic, propy lic, isopropylic, and amylic), under the conditions employed, give entirely negative results either in presence or absence of iron. But in the case of all the polyhydric alcohols examined (ethylene glycol, glycerol, ery thritol, mannitol, dulcitol, and sorbitol) it is found that the presence of ferrous iron exerts a remarkable influence on oxidation by means of hydrogen dioxide.In the absence of iron, practically no change is produced, but, in its presence, very considerable rise of temperature occurs in all cases, and the alcohol is vigorously oxidised. Ethylene glycol yields glycollic aldehyde, but apparently no glyoxal. With glycerol, the product appears to be glyceraldehgde with little or no dihydroxyacetone. From erythritol, a product yielding erythrosazone is obtained, and mannitol gives mannose. The yields, generally, are remarkably good as compared with those obtained by oxidation with nitric acid, kc., and in this way it is easy to obtain mannose directly from mannitol without first preparing the hydr-azone. The authors are attempting to isolate tetrose in a similar way. As in the case of tartaric acid, it is found that certain of these polyhydric alcohols may be similarly oxidised by atmospheric oxygen in presence of ferrous iron and of sunlight.145. The occurrence of hyoscyamine in the Hyoscyamus muticus of6‘ India.” By Wyndham It. Dunstan and Harold Brown. The authors find that the stem and leaves of the Indian HYOS-cyamus muticus contain about 0.1 per cent. of hyoscyamine, and that the alkaloid can be extracted in a pure state from this plant more readily than from ordinary henbane. The plant is fairly abundant in the Punjab and Beluchistan, and is likely to prove of value both as a drug, and as a source of hyoscyamine. 247 DISCUSSION. Professor DUNSTAN,in reply to Mr. GROVES,Mr. DAVIDHOWARD, and Mr.PAGE,said it was possible that age and climate might have some influence in changing the hyoscyamine and forming other mydriatic alkaloids. There was every reason to believe that the physiological action of the drug was principally due to the alkaloid it contains, and not to any other constituent. Dr. W. H. Perkin, F.R.S., then took the Chair, and the following paper was read :-146. “The comparative colour of the vapour of iodine in gases at atmospheric pressure and in a vacuum.” By James Dewar, LL.D., F.R.S. Recently, having had occasion to compare iodine with other sub- stances as a means of obtaining vacua in the construction of vessels used for the storage and manipulation of liquid air in low temperature research, some facts about the behaviour of the vapour of iodine have been observed which deserve to be recorded.Pure iodine in the solid state is usually stated to be perfectly opaque to light, but this is not the character of iodine distilled and condensed on a surface of glass at temperatures between -180’ and -190’ in vacuum test tubes or bulbs by the use of liquid air. Under such conditions, it is easy to get transparent films of iodine of varying grades of thickness showing brilliantly the colours of thin plates by reflection, and to keep them permanently as long as the low temperature is maintained. The first addition of liquid air to the vacuum bulb or test tube containing excess of solid iodine causes instant precipitation of an opaque film, but this can be avoided by cooling the iodine, which has been caused to sublime to the lower part of the outer test tube or bulb, by a pre-liminary treatment with a little solid carbon dioxide.In this condition, when the inner surface of the vacuum vessel is cooled with liquid air, the iodine can only deposit from an atmo-sphere of great tenuity, and when a given thickness of deposit is reached, any increase can be stopped by removing the vessel from the liquid carbon dioxide and placing it in liquid air. In the same way, films of other substances can be deposited which may be useful in the examination of many physical problems. Stas says that pure iodine gives no visible vapour at the ordinary temperature, but this is contrary to the author’s experience.Samples of iodine, ob-tained from cuprous iodide, from iodoform, and from solution of iodine in potassium iodide, and in sufficient quantity to ensure satura- tion, gave,in half-litre flasks, a visible colour to the atmosphere at the 242 ordinary temperature. When, however, a similar flask containing the same iodine was exhausted of air, the colour of the atmosphere mas markedly less, and this distinction remained even when the flasks were heated side by side in a water bath. If the iodine vapour diffused into an atmosphere of carbon dioxide, hydrogen, or oxygen, in similar flasks, instead of into air, the colour remained the same; but in all cases it was much more marked than in one from which the gaseous atmosphere, other than iodine, had been in great part removed by the air pump, No change in the mode of filling the air and vacuum flasks made the difference in colour disappear, although a dozen flasks have been filled from time to time.No change in the character of the results was effected by subliming the iodine from anhydrous baryta and keeping it in flasks for months with excess of the latter, nor was any apparent difference produced when the flasks containing the baryts were repeatedly heated at the boiling point of water. This seems to prove that neither water vapour nor hydrogen iodide has anything to do with the cause of the difference in colour of the iodine vapour in the air and vacuous flasks. It is not necessary to use flasks, as two lengths of glass tubing, an inch or less in diameter and a foot or more in length, when heated side by side in a steam or water bath, show the difference of colour.To obtain an approximate value of the tension of the saturated vapour of iodine at about the ordinary temperature, a Rankine formula of two terms was calculated, taking the known pressure at 58.1' as 4-9mm. and that at 113.8' as 87 mm. These gave :-(1) log P=9.3635--2872 17 mm. If, however, the tension at 85O and 11 4-1' are selected for calculation, (2) log P=10003923137-mm., where F 2' is the absolute temperature. From formula (1) the tensions in mm. of mercury0' at and 113 are respectively 0.07 and 0.18. The weight of iodine in a litre would thus become about 1 and 1-94 check this calculation, toorderInrespectively.11'and 0'milligrams at the quantity of iodine required to saturate a litre of dry air at Oo and 11' was determined by passing a slow current of air over a column of the substance and subsequently absorbing the iodine from the saturated air by passing it through a caustic potash solution.The alkaline solution, after acidifying, was titrated with sodium thiosulphate. The results of the experiments were as follows :-Milligrams per litre. Pressure in mm. of mercury. O0 0.24 0.017 1lo 1*25 0-087 30" 4.70 0.368 243 In each case, the calculated tension is less than that deduced from the first vapour pressure equation. The values approach those given by Arctowski (Zeit. Alzorg. Chm., 1896, 12, 427) as a deduction from his experiments on the volatilisation of iodine.From this, it would follow that the second equation for the tension is the better. In the liquid state, the tensions are well represented by (3)log P =7.924 2316 mm.T From formula (2): the molecular latent heat of solid iodine is 14430 units, and for the liquid condition from (3) the value is 10653. The experimental value of the latent heat of liquid iodine given by Favre is 6000 units. From this, it would follow that the latent heat of volatilisation requires to be redetermined, It is interesting to observe that the number of heat units required to dissociate the molecule of iodine is 28500, or roughly, twice the calculated latent heat of the solid.The various experiments recorded lead to the conclusion that the phenomenon is a real one, although some factor that has been neglected may explain it ;at any rate, it is difficult to avoid getting the result. Assuming it to be true, its explanation then remains to be considered. It is well known that the vapour pressure in a vacuum is often greater than in air at atmospheric pressure. On the other hand, Professor J. J. Thomson, in his work entitled Alrplication of Dynamics to Physics and Chemistry,p. 169, discusses this very question. He shows that the effect of the pressure of an inert gas must be to raise the vapour pressure of a substance diffusing into it above that produced by the diffusion of the same substance into a vacuous space.Taking the equation which he there developed as being applicable to iodine, the difference between the two conditions of pressure should amount to of the whole. Now the question arises whether this amount is sufficient to explain the difference of colour or whether it is necessary to bring in other factors which may operate, such as solution of solids in gases under pressure, dissociation, or want of equilibrium. Further experiments will be required before a definite answer can be given. Hannay and Hogarth first showed that alcohol vapour above its critical point, and therefore at a pressure above 60 atmospheres, can dissolve solids like potassium bromide or iodide, and Cailletet, a little later, found that liquid carbon dioxide was dissolved by air under high compression.Dr. Villard has recently made a series of experiments on the same subject, in which he proves that bromine and iodine dissolve in air or oxygen under high compression. He says: I‘ L’iode se dissout egalbment en quantiti: sensible dans l’oxygdne, mais le phbnorn&ne n’est bien visible qu’a partir de 100 atmospheres et dans des tubes de 5 millimetres de diametre au moins.” 244 The experiment exhibited would appear to show that the pressure of one atmosphere is sufficient to produce a sensible difference of colour in the case of iodine vapour diffused in air and in a vacuum. For the present, it may be regarded as :t lecture illustration of the rapidity of volatilising iodine in an air space as contrasted with a vacuous one.DISCUSSION. Dr. THORPEthought that the phenomenon which the President had brought to the notice of the meeting was highly interesting and sug- gestive. It seemed to him, after watching the experiment shown to them during its whole course, that the character of the colour of the resulting vapours was so markedly different as to lead to the inference that something more than a mere dilution of colour due to an actual difference in the amount of vapour present had occurred, He could not help comparing the phenomenon with the well-known difference in colour of various solutions of iodine in alcohol, carbon disulphide, chloroform, &c., and thinking that molecular dissociation was taking place. Perhaps in this connection it might be worth while to make a comparative spectroscopic study of the vapours in the two con-ditions. Professor F.D. BROWNsaid that he, too, had remarked the much browner colour of the iodine vapour in the vacuous tube, Remem-bering the fact that iodine in brown solutions is in a different molecular condition from that in violet solutions, it seemed probable that the vapours in the two tubes were also in different molecular conditions. With regard to the suggestion that the iodine was in some way dissolved in the gas, he stated that one of his students in New Zealand had ascertained that equal volumes of different gases at the same temperature and pressure took up exactly equal quantities of iodine, whereas it was probable that if iodine dissolved in a gas as a solid dissolves in a liquid differences in solubility would have been found.Mr. ELWORTHY,in reference to the solubility of solids in gases at temperatures above their critical points, and under pressure, said that when in Bombay he gave instructions for some vulcanised rubber to be placed in a vessel with carbon dioxide at about 5 or 6 atmospheres pressure; instead of this, about 5 pounds of the gas were introduced into a vessel usually employed to contain 15 pounds of liquefied carbon dioxide. At temperatures below the critical point a certain amount of liquefied gas would have been present, but as the temperature was between 87" and 90' F., the gas was in the condition of a vapour under pressure.On opening the vessel and allowing the gas to escape, it was found that practically all the sulphur had been dissolved out of the 245 rubber, the surface of which was covered with a thin crust of sulphur crystals. Mr. L. M. JONESasked whether any attempt had been made to determine the actual concentration of the iodine in the two cases ;and also whether the apparent solubility of a solid in gas at high pressure might not be actually due to the increase of vapour pressure predicted by Professor J. J. Thomson. Dr. TRAVERSpointed out that the critical phenomena observed when the air confined over liquid carbon dioxide was compressed at constant temperature could not be produced by conditions similar to those which were present in the case of the iodine and air.When air was compressed in contact with any liquid, it dissolved and produced a mixture of constantly decreasing critical temperature. Consequently, supposing that sufficient air were present, it should in any case be possible by exerting sufficient pressure to produce a mixture whose critical -temperature was the temperature of the experiment. The phenomenon could have nothing to do with the solution of the solid or liquid in the gas. Dr. FORSTERinquired whether iodine had been imprisoned in atmospheres other than a mixture of nitrogen and oxygen. If, as was suggested, the phenomenon in question is a case of solution, differences in appearance similar to that subsisting between solutions of iodine in alcohol and in carbon disulphide, might be expected in tubes containing iodine enclosed with various inert gases.The PRESIDENT,in reply, said that the spectroscope had not been used in his experiments, and bearing in mind the character of the absorption spectrum of iodine, he anticipated it would be difficult to obtain any information as to the character of the phenomenon by its employment. The possibility of dissociation had not escaped atten- tion, having been mentioned in the paper. All that he could say was that at present he could not specifically state that the difference in the behaviour of iodine under the two conditions was due to one or other of the possible causes to which he had referred. Iodineenclosed in tubes containing gases such as carbon dioxide, nitrogen, hydrogen, and oxygen gave appearances indistinguishable from those observed in similar tubes containing air.NOTICE TO AUTHORS. As the Proceedimp go to press on the Monday after each ordinary Meeting of the Society, the announcement of papers for the next Meeting cannot be made in this publication unless the papers are in the hands of the Secretaries by noon on that day. 246 At the next meeting, on Thursday, December 15th, the following papers will be communicated :-‘‘ The interaction of ethylic sodiomalonate and mesityl oxide.” By Arthur W. Crossley, Ph.D. ‘‘Derivatives of camphoric acid, Part 111.” By F. Stanley Kipping, D.Sc., F.R.S. ‘‘Synthesis of aPP-trirnethylglutaric acid.” By W. H. Perkin, jun., and J. F. Thorpe. RlCHARD CLAY AND SONS, LIMITED, LONDON AND BUNCAY.
ISSN:0369-8718
DOI:10.1039/PL8981400239
出版商:RSC
年代:1898
数据来源: RSC
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