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Proceedings of the Chemical Society, Vol. 7, No. 99 |
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Proceedings of the Chemical Society, London,
Volume 7,
Issue 99,
1891,
Page 103-112
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摘要:
Issued 13/6/1891. PROCEEDINGS OF TEE CHEMICAL SOCIETY. No. 99. Session 1891-92. June 4th, 1891. Mr. William Crookes, F.R.S., Vice-president, in the Chair. Messrs. F. Stanley Kipping and Mr. Ernest F. Hooper were form- ally admitted Members of the Society. Certificates were read for the first time in favour of Messrs. William A. S. Calver, 45, Barrington Road, Brixton, S.W.; John William Heap, 33, Upper Gloucestcr Place ; Robert Lennox, 3, Inver-ness Terrace, Putiiey, S.W. ; Rudolf Laurentz Leffler, 21, Havelock Street, Sheffield ; Charles K. Scott, 26, Pigott Street, Limehouse, E, ; Thomas Stephenson, Rellasis Road, Byculla, Bombay ; Henry White, 8, Brown Street, Masboro’, Rotherhsm. The following papers were read :-24. “ The molecular refraction and dispersion of various substances in solution.” By Dr, J.H. Gladstone, F.R.S. The paper is a continuation of that laid before the Society in March Isst, and deals entirely with solid and gaseous substances that have lieen dissolved in water or other liquids for examination. The results are given in several tables. It cannot be expected that there should be anything like the same accordance between the experimental and calculated numbers as is usually fonnd in the case of pure liquids, as in weak solutions the experimental error is greatly multiplied. Nevertheless, in the case of organic compounds, the agreement is frequently very close. Terpene hydrate and terpilene dihydrochloride appear as saturated compounds, and so do camphor and its derivatives :but lnenzyl camphor, CIjHJ3, and benzal camphor..104 C,,H,,O, substances recently prepared by M. Haller, give results, especially in dispersion, which are far in excess of what might have been anticipated. The sugar group presents some peculiarities. Cane sugar seems to show a refraction, and especially a dispersion, rather smaller than theory. Milk sugar, dextrose, and glucose are fairly accorda.nt with theory ; while mannitol, on the other hand, seems a little high in refraction. Hydrogen chloride, bromide and iodide give figures for the mole- cular refraction and dispersion much higher than the sum of the hydrogen and the halogen as determined from the paraffin com-pounds, and the values rise as the dilution becomes greater.Peculi-arities analogous to this had previously been discovered by Perkin in regard to their magnetic rotation. Seleniom and selenic acids, like the analogous sulphur compounds, afford optical values vastly less than what would be expected from the known values of their con- stituents. Metaphosphoric acid does the same. The data relating to solutions of salts and alkalis, including compounds of aluminium, ammonium, barium, calcium, cerium, chromium, didymium, iron, iridium, lead, lithium, lanthanum, magnesium, potassium, silver, sodium and tin. It will afford material for a revision of the refraction equivalents of the diffe- rent metals, and of the electro-negative elements with which they are combined. They will also furnish additlional means for deter-mining the dispersion equivalents.Among the points noted are the following :-Ammonia, in strong contrast with the hydrides of chlorine, bromine and iodine, appears to he uniform in its optical properties, whatever the strength of the solution ; it agrees with what would be expected from theory. The refraction equivalents of cerium, didiym- iurri and lanthanum are deduced from their salts at about 12.4, 16.4and 15.5 respectively. The chlorates, broruates and iodates are sufficiently represented to give an idea of their optical characters. At first sight, it would appear that the addition of 30 to the haloid salts causes an inadequate increase of the molecular refraction, and a slight actual decrease in the molecular dispersion. But this probably arises from the fact that the haloid salts themselves, when dissolved in water, give a somewhat excessive value.The molecular refraction for C103 in its salts dissolved in water comes out at about' 18.3, that for BrO, at 24.9 and for 10,at 33.8. DISCUSSION. Dr. PERKINremarked that there was a, close agreement between Dr. Gladstone's conclusions and those which he had arrived at from 105 the study of magnetic: rotatory power. The very high values afforded by the elements sulphur and phosphorus, in comparison with the values deduced for these elements from sulphuric and phosphoric acids, were very striking. The magnetic rotatory power of caustic soda was also very high. Dr. GLADSTONE,in the course of remarks on Dr.Perkifi’s comments, said that it was particularly noteworthy that sulphur retained its high value in carbon bisulphide. LL25. The nature of solutions as elucidated by a study of the densities, heat of dissolution and freezing points of solutions of calcinm chloride.” By S. U. Pickering. The curves representing these properties were examined in the same way as those representing various properties of sulphuric acid, and similar conclusions are drawn in the two cases, namely, that definite changes of curvature occurs at certain points which are the same, whateyer property is examined, and which coincide, in all cases where such a coincidence can be ascertained with certainty, with simple molecular proportions of the salt and water ; and, consequently, that these changes represent the existence of hydrates in solution. The simplest hydrates indicated in the present case consist of CaC1, with 6, 7 and 8H,O ; more complex hydrates exist also, as in the case of sulphuric acid.26. “Note on a recent criticism by Mr. Sydney Lupton of the conclusions drawn from a study of various properties of sulphuric acid solutions.” By S. U. Pickering. Mr. Lupton (Phil. -Mag., 31,418) applies a single parabolic equa- tion to a portion of one of the author’s sulphuric acid density curves, wliere a change of curvature was supposed to exist, and shows that it represents the results accurately if the experimental error is of a certain magnitude. This magnitude, however, is between 1000 and 10,000 per cent. greater t’han the ascertained magnitude, and the equation, moreover, represents all the errors of like signs as being grouped together.Such a representation cannot disprove the exist- ence of the particular change of curvature under investigation, still less that of the 101 others shown in the various curves examined by the author. The hydrate on which Mr. Lupton considers that his investigation throws ‘’very grave suspicion ” happens to be the one which tbe author has isolated in the crystalline condition. 106 Discussiox. Professor RAITSAYdoubted the validity of Mr. Pickering’s methods of differentiating his curves. His own experience was that it mas impossible to obtain Fesults nearcr tlian 2 or 3 per cent.to the truth, with a curve drawn as carefully as possible, and a straight steel-edge laid along it to obtain tangents. Mi.. Pickering, on the other hand, pursued a much more crude method, viz., he directly connected his experimental points by straight lines, and took the slopes of such lines 2,s the tangents to his curves. This obviously did not eliminate any experimental error, but rendered it more marked. Dr. ARXSTRONGsaid that he had no desire to intervene in the dis- cussion which had arisen as to the validity of Mr. Pickering’s method. It appeared to him, however, that Mr. Pickering’s con-clusions were ia many respects open to question from a chemist’s point of view ; he thought, in fact, that 3fr. Pickering both proved too much and was illogical.Prepared as the speaker was to believe in the existence of hydrates in solution, hc could not imagine that so large a number as was suggested would arise, or that the 102 breaks in the sulphuric acid curves, for example, could possibly be iater-preted as evidence of as many distinct hydrates. There was no in-dependent evidence to support such a conclusion. Then he thought Mr. Pickering was illogical, because he in-terpreted all the breaks as indicative of hydrates, notwithstanding that lie asserted-doubtless, with justice-that both water and sulpli- uric acid in the pure state consisted of complex molecules : surely in this case, as change woizld set in at either end of the curve, it must be impossible to say which of the breaks are to be rcgarded as indicative of change in the composition of the complex molecules of acid and water respectively, which are due to the formation of hydmtes consisting of simple water and acid molecules, and which are due to the formation of hydrates, say, of simple water and complex acid molecules.With regard to Mr. Pickering’s contention that Mr. Lupton must be wrong, because the latter had dealt with the part of the curve which included that hydrate which of all others was the best characterised hydrate of sulpliuric acid-a hydrate that he had pre-pared before them in tlie room--L)r. Armstrong said that, from experiments which were being carried 011 in his laboratory, he was inclined to believe that the said hydrate probably did not begin to form in solution until the temperature sank to within a few degrees of its point of fusion: it might well be therefore that it was not present in the solution to which Mi*.Lupton’s conclusions related.107 The more the speaker studied these questions experimentally, the more inclined he became to think that changes of composition, whenever they occurred, were indicated on curves drawn directly to represent the experimental results. Dr. MORLEYsaid that ihappeared to him that, even if Mr. Pickering was correct as to the number and position of breaks in the curves, it by no means followed that he had proved the existence of the par- ticular hydrates suggested. A break in the curve should indicate that some new hydrate had just begun to form, but need not show what that hydrate was.Thus it was probable the hydrate CaCI28H,0 would begin to form before the entire liquid contained a percentage of calcium chloride corresponding to that formula; and when the liquid had attained that composition, it might be expected to contain, besides tho hydra.te CaC1,8H20, also higher and lower hydrates, such as CaCl,SH,O and CaC1,7H20. Professor RUCKEK,while fully admitting that the concordance of the numbers obtained by Mr. Pickering from observations on differ- cut physical properties of the solutions might fairly be urged in his favour, thought it important that the agreement between results all of which depended on the application of the same method should not be regarded as conclusive evidence in its favour if it were otherwise open to grave doubt.In reality, Mr. Pickering’s results were obtained, not by calculation, but by a method of observation and experiment applied to curves, which themselves represented the results of other experiments. The instrument used was a flexible ruler. It was admitted that the curves had to be specially drawn and the scale of the coordinates carefully chosen, if the results were to be satisfactory, and it was difficult to believe that the conclusions arrived at did not in large measure depend on the details of this preliminary adjustment. At all events, as in the case of all other experimental methods, the final test of validity is whether concordant results are obtained by different observers, arid it was therefore important that those who had personally tested it should give the results of their experience.The speaker had himself gone over Mr. Pickeriug’s work in the case of one of the sets of observations on the densities of dilute sulphuric acid of different strengths, and he could bear witness to the care with which the curves were drawn. Nevertheless, the con- clusion he arrived at was precisely similar to that which Professor Armstrong had expressed. In the case of the more striking changes in direction and curvature which were clearly visible in the original curve, the various differ- ential curves did not add much to the information it supplied. On the other hand, he thought that the evidence afforded by these 108 secondary curves of changes of curvature, which could not otherwise be detected, was of the most untrustworthy character.The assumption seemed often to be made that, because the results of experiments were more closely represented by two curves than by one, there must be a discontinuity, which was evidence of some physical change. That this conclusion might be fallacious is evident from the fact that, if a sufficient number of discontinuities were ad- mitted, the results of experiment might be represented graphically with absolute fidelity. His experience of the method would lead him to doubt any conclu- sions based upon it alone and not supported by independent evidence.It became untrustworthy just when it professed to become useful, by supplying information which could not otherwise be att'ained. Mr. PICKERINGsaid that Mr. Lupton's equation represented the rate of change of the densities as a straight line, while the figure which the actually observed rate of change formed was as different from a straight line as could well be imagined (C. 8. Trans., 1890, 80). The straight line might be regarded as fitting a greater or smaller portion of this experimental figure, according to the latitude allowed to experimental error. In order that it should fit thaf portion of the figure which Mr. Lupton said it did, the latitude to be allowed would have to be 10 to 100 times greater than that for which there was any warrant.This, be considered, was not allowable. The figures here referred to (and exhibited at the meeting) were the first differential figures (rate of change) deduced directly from the deter-minations themselves ;the question, therefore, of the accuracy attain- able in differentiating a graph, raised by Professor Ramsay, did not apply to them. It seemed somewhat rash of Professor Armstrong to hold that a particular hydrate (H2S044H20)did not exist in solution at mode- rately high temperatures, because from a study of one property he had recognised it at low temperatures only, especially as it was from his own results at high temperatures that the speaker had been led to search for it, and finally to isolate it, at low temperatures. The multiplicity and complexity of the hydrates indicated must, no doubt, endanger the acceptance of his conclusions amongst chemists ; but without reason, he thought, for we are at present in the dark as to the nature of liquid molecules (see Zoc.cit., pp. 124, 129). He would be perfectly ready to accept any other explanation of the changes with weak solutions than that of their being due to hydrates, but he considered that we have at present no evidence in favour of any other view, or of their being due to changes in the aggregation of the solvent molecules, while the fact that they are precisely similar to the changes with strong solutions which occur at simple 109 molecular proportions forces us to attribute them to the same cause as t’he latter,, until some evidence to the contrary be forthcoming.He had already alluded to the question raised by Dr. Morley, as to why the existence of a hydrate should cause a change of curvature at exactly the strength of the solution corresponding to it (Zoc. cif., p. 138), but he had left that question to those who had sufficient mathematical abilities do deal with it. Mendel&eff, however, appeared to consider that no exception could be taken on that score (C. 8. Trans., 1887, p. 779). The fact mentioned by Professor Rucker, that a flexible spring could be made to fit any complicated curvilinear figure by fixing it in position by a sufficient number of pins, did not appear to disprove the existence of defiinite changes of curvature in the figure ; for the forces acting on the spring between any two given pins would be different from t,hose .acting on it between any other two; and, con-sequently, the form of the different portions of the spring would be represented by different equations, that is, there would be changes of curvature.He did not see how the position of these changes of curvature could be said, on either theoretical or practical grounds, to depend on the flexibility of the spring used ; for he believed he was correct in saying that all springs, when acted on by forces of a similar nature, assuiiied similar forms, and any difference in the degree of curvature due to a difference in flexibility might be counteracted by a difference in the magnitude of the forces applied.In practice, he had used numerous springs of very different degrees of flexibility, without finding any difference in the position of the changes of curvature indicated. It seemed scarcely correct to say that the application of a flexible lath to a curvilinear figure led to different results in different hands, because MendeGeff’s conclusions respecting the densities of sulphuric acid differed from the speaker’s; for Mendeleeff had an altogether insufficient number of experimental point,s at his disposal, and, its far as could be judged, did not use a flexible lath at all in examining them. The question as to whether a lath could or could not be used in locating changes of curvature which were not apparent to unassisted inspection might be most easily settled by submitting a fictitious series of determinations, calculated from sundry different equations, to examination with a lath, and ascertaining whether the position of the changes of curva-ture found coincided with those at which the equations had been changed. He was quite ready to submit his process to this crucial test.110 27. "Ethylic ad-dimethyl- %a'-diacetylpimelate and its decomposi-tion products." By F. Stanley Kipping, Ph.D., L).Sc., and J. E. Mackenzie, B.Sc. When diacetylpentane is reduced with sodium and moist ether it is converted into dimethyldihydrovyheptamethylene (cf. Kipping and Perkin, 0. 8. Trans., 59, 214), according to the equation +CHz*CH,*CO*CH, zH = cH2<CH,.CH,*~(OH)'CH~CHZ< CH2.C: H,*CO*CH, CH2*CH2*C(OH) *CH,' As it seemed probable that other 1: 7-diketones would behave in a similar manner, the authors have prepared aa'-dimethyl-ad-diacetyl-peritane by the method described helow.The action of reducing agents on this diketone is now being investigated by one of them, but, as a considerable amount of work has yet to be. done on the subject, they describe in tJhepresent paper the preparation and piaoperties of dimethyldiacetylpentane and of various other compoun ds obtained in the course of the research. Ethylic aa'-dirnethyZ-aa'-diacet~~imelnte, CO,E t*CMeAc-[CH,] 3*CMeAc*COzEt, is formed in considerable quantities when ethylic sodiornethylsceto- acetate (2 luols.) is treated with trimethjlene bromide (1mol.) in abso-lute alcoholic solution ; it is a colourless oil boiling at 233-235" under a pressure of 50 mm., and it combines readily with phenylhydrazine (2 mols.) yielding a reddish-yellow dihydrazorle, which has the com- poyition C,9H40N404.On boiling with alcoholic potash the ethereal salt is readily decomposed, the principal products being aa'-dirnethyl- aa'-diacetylpentane, ad-dimethyl-a-acetylcaproic acid, and aa'-di-me thylpimelic acid.ad-Dillletlay I-aa-dincety~entnne, CH,*CO*CHMe*[CB2]3-CHMe*CO*CH3, is a colourless liquid boiliiig at 202-204" under a pressure of 150 mm. ; when treated with hydroxylamine it is converted into a crys-talline dioxime, C,,H2,N,O,, which melts at 93-94'. aa'-Dimethy I-a-acety lcaproic acid, CH,*COCHMe*[CH,],*CHNe-COOH, is a colourless oil boiling at 226-228' uiider R pressure of 70 nilti, seemingly with slight decomposition.The silver salt, CloHl,O,Ag, ethylic salt, CI,&,O3, rnethylic salt, CllHZ0O4,and the hydroxinae, C10H19N03,are described. ad-DirnetkyZpimslic acid, C02H*CHMe*[CHzI3*CHM e*C02H, sepa- rates from light, pstroleum in well-defined crystals, melts at 80-81", 111 and is readily soluble in most crdinary solvents. The si7.r.e~salt,, C9HI4O4Ag2, were prepared. and the barium salt, C9H1404Ba, EthyZic-ad-dimethyZpimeZate, COOEt*CBMe*[CH2]3*CHMe*COOEt, is formed in the place of ethyl dimethyldiacetylpimelste when tri- methylene bromide is treated with ethyl sodiomethylacetoacetate in alcoholic solution, the alcohol employed being not quite anhydrous ; it is a colourless oil boiling at 190-191", under a pressure of 80 nim.28. "Volatile platinum compounds." By W. Pullinger. At Professor Lothar Meyer's snggestion, the author has further studied the volatile compounds of platinum with chlorine and carbon monoxide described by Schutzenberger, with the object, if possible, of determining their vapour density. He describes their behaviour when heated in various gases ; as they do not completely volatilise, even in carbonic oxide, he was unsuccessful in accomplishing his obj ec t. In preparing the compounds, he has obtained a novel compound of the formula PtC1,C20, as a non-volatile, yellow, crystalline solid, easily soluble in water, and recoverable apparently uncbar,ged from the solution.Liquid carboiiyl chloride at 100" is found to act as n solvent of Schutzenberger's compounds, depositing them on cooling in large crystals. The aiithor has prepared the compound PtBr2C0 by heating plati- nous bromide in an atmospliere of carbonic oxide ; apparently it is the only product even when excess of the gas is used. It crystallises in well-defined needles melting at 177", and volatilising with extreme difficulty, even in an atmosphere of carbonic oxide. Directions are given for the preparation of platinic bromide and iodide, from which it appears that platinum sponge readily dissolves when merely boiled with either a solution of bromine in bromhydric acid or of iodine in iodhydric acid.DlscussloN. Dr. COLLIE mentioned, as an instance of a volatile metallic deriva- tive, that he had recently had occasion to notice that the copper derivative of the double ketone diacetylmethsne, (Ac~CH)~CU,was volatile. 112 At the next meeting, on June 18th, there will be a ballot for the election of Fellows, and the following papers will be read:- “The action of sulphuric acid on dehydracetic acid.” By Dr. Collie. ‘‘ The refractive power of certain organic compounds at different temperatnres.” By Dr. W. H. Perkin, F.R.S. “ The formation of salts-a contribution to the theory of electro-lysis, and of the nature of chemical change in the case of non-electrolytes.” By Henry E. Armstrong. IIAERISOB AND SONS, PRIRTERS Ih’ ORDINARY TO IIER MAJESTY, ST. MARTIN’S LANE.
ISSN:0369-8718
DOI:10.1039/PL8910700103
出版商:RSC
年代:1891
数据来源: RSC
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