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Abstracts of the Proceedings of the Chemical Society, Vol. 3, No. 37 |
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Proceedings of the Chemical Society, London,
Volume 3,
Issue 37,
1887,
Page 57-62
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摘要:
ABSTRACTS OF THE PROCEEDINGS OF THE CHEMICAL SOCIETY. No. 37. Session 1887-88. April 21st, 1887. Mr. William Crookes, F.R.S., President, in the Chair. Mr. T.H. Redwood was admitted a Fellow of the Society. Certificates were read for the first time in favour of Messrs. Ernest Francis Ehrhardt, B.Sc., Hillcrest, Richmond Hill Road, Edgbaston ; Henry Hewetson McMinnes, Agricultural College, Roseworthy, Adelaide, South Australia ; John William Young, B.A., G-uilford Lodge, Brentwood. The following mere elected Fellows of the Society :-Messrs. W. C. T,Beasley ; Edward R'. Blundstone, B.A. ; Samuel F. Burford ;James W. Chenhall; George Collar, B.A.; Henry Danber, jun.; Hugh Gordon ; William Gregory ; David Lloyd Howard ; Edward Rawlins ; Louis H.Schubert ; Leonard 0. Simmons ; Samuel Sutcliffe. The following Papers were read :-37. " The Atomic Weight of Gold." By T. E. Thorpe, F.R.S., and A. P. Laurie, B.A. Former determinations of the atomic weight of gold have been made by Dalton, Proust, and Oberkampf, in 1806; Rerzelius, in 1813; Pelletier, Javal, and again by Berzelius, in 1844; by Levol, in 1850; and Thomsen, in 1876. The numbers obtained differ widely from each other, partlyowing to the unstable character of the salts of gold, and partly to imperfect methods of analysis. The number usually accepted is 196.2, being the value obtained by Berzelius in his second series of deterrnitiations, from the analysis of the double chloride of gold and potassium. A special reason for undertaking a revision of' the atomic weight of gold arises from the circumstance that a higher value than that usually assigned to this element is dem'anded by the periodic law.The salt employed by the authors is the bromide of gold and potassium, which crystallises readily from water, and (as proved by a series of analyses of different crystallisations) is stable at ordinary temperatures. The salt was prepared by digesting together gold, water, bromine and potassium bromide, and was then three times crystallised. The method of analysis was as follows :-About 15 grams of the double salt was introduced into a large porcelain crucible, carefully dried in an air-bath, and then decom- posed by heating over a Bunsen flame. The crucible containing the mass of decomposed salt was weighed against a similar and similarly treated crucible, the bromide of potassium washed out with hot water, the solution being drawn into a bottle by reverse filtration, and the gold ignited in a muffle, and again weighed.From these weighings the first set of values for the atomic weight was calculated. A weighed quantity of silver (the purity of which had been tested at the Mint by comparison with the trial plate) was dissolved in dilute nitric acid and added to the potassium bromide, and the excess of the potassium bromide precipitated by a solution of silver nitrate of known strength. From these results the second series of values was calculated. The silver bromide was then collected, dried at 160" C., and weighed.From these weighings a t,hird series of values was calcul ahed. On comparing the weight of silver used with the weight of bromide of silver obtained, the ratio between them was found to be Ag :AgBr = 1:1-74072. According to Marignac, Ag : AgBr = 1 : 74077. According to Xtas, Ag :AgBr = 1: 1.74081. The close agreement of these ratios with that obtained by the authors is a proof of the absence of chlorine in the bromine or potassium bromide employed by them in the formation of the double salt. The ratios assumed between Ag, Er, K, 0, and H were those of Stas, and are as follows :-Ag.. ........................ 6.7449 Br.. ....................... 4.99634 K .......................... '2.44523 0 ..........................1 H .......................... 0.06265 On the basis of these numbers, the results of the various obserra- t,ions may be thus summarised :- 59 Series 1. (8 Experiments). Au : KBr ................ 37~49137:22.61944 ................ 1.65748:l99 Au : 0 .................. 12.3343 Au :H .................. 196.876 Series 11. (9 Experiments). AU :Ag .................. 41.67403 :22.7937'4 ,. .................. 1-82831 :1 Au :0 ................... 12.33'18 Au : H .................. 196.837 Series III. (8 Experiments) . Au : AgBr ................ 36.50997 :34.76060 .................. 1.05033: 1 Au: 0 ................... 12.3322 Au: H .................. 196.842 On the assumption that these values have equal weight.the final value from the whole 25 experiments becomes- Diff.from mean. Series I............ 196.876 + 0.026 .. I1............ 196.837 -0.013 .. I11............ 196.842 .-0.008 Mean ....... 196.850 When a considerable portion of the determinative work connected with this investigation had been accomplished. it paper on the same subject appeared in the Berichte for February. 1887. by Rruss. Kruss also used potassium bromaurate. but his method of treating the salt differed somewhat from ours. The following table contains a summary of his results :-AU (H = 1). 1. Au : KBr.Br, (9 experiments) ..... 196.741 I1. Au : Bra (5 experiments).......... 196.743 I11. Au :Br3(4 .. ).......... 196-619 IV. Au : KBr (4 experiments) ........196.620 He also analysed a neutral solution of auric chloride. obtaining the value Au = 196.594. He adopts as the most probable value Au =196.64. DISCUSSION. The PRESIDENT,after referring to the great value of such investiga- tions, said that he should have been glad to have heard more from the authors regarding their method of weighing, and of the means they had adopted to control the accuracy of their weights, and to correct for the buoyant effect of the air ; the errors incidental to the operations of weighing were often greater than the minute errors involved in the chemical operations. The quantities of material used in the various experiments appeared to him to be very small ; never-theless the agreement between the results of the several experiments was highly remarkable.Professor THORFE,in reply, said that they had endeavoured to eliminate the corrections necessary on account of buoyancy, and of changes due to deposition of films of moisture, &c., by always using as a tare to the apparatus weighed a precisely similar apparatus which had been treated in the same way. The argument that the same result would have been obtained by means of a single experi- ment by taking the aggregate amount of salt used in all the experi- ments together presupposed that the errors of a seiliea of experiments were all in one direction : buk this was not the case. 38. "The Atomic Weight of Silicon.'' By T. E. Thorpe, F.R.S., and J. W. Young, B.A.The authors have attempted to redetermine the atomic weight of silicon by estimating the quantity of silica yielded by decomposing known weights of silicon tetrabromide by means of water. The results of their experiments are seen in the following table :-Wt. of SiBr, ir, mvcuczc'o. Wt. of SiOp im vacuo. Si (H = 1). 9 *63007gpams. 1-67070 gramR . 28 * 347 12.36099 ,, 2-14318 ,, 28 '303 12'98336 ,, 2-25244 ,) 28'347 9.02269 ,, 1.56542 ,, 28 -352 15.384126 ,, 2-66518 ,, 28 *243 9.74550 ,, 1.690261 ,, 28-325 6.19159 ,, 1.07536 ,, 28 -429 9.51204 ,, 1.65065 ,, 28 -366 10'6931'7 ,, 1-85555 ,, 28'364 The aggregate weight of the silicon tetrabromide employed in the various experiments was 95.52367 grams ; it yielded 16.56868 grams silicon dioxide.Assuming with Lothar Meyer. and Seubert that the most probable ratios for the atomic weights involved in the calcula- tions are- Br .................... 4.99721 0 ...................... 1 €I...................... 0.06265 the above numbers give as the atomic weight of silicon 28,332 if H = 1. The previously recorded values are all based upon the ratios of equivalent quantities of silicon tetrachloride, silver and silver chloride, and were obtained by using comparatively small quantities, i.e,, 1to 2 grams of the chloride. They are as follows :-1Date. Authority. Method. KO.of expts. Si (H = 1). I------I----I--I 1845 .... Pelouze SiC1, :Ag 2 28 -4.11 11859 .... Dumas Sic14 :Ag 2 27 *99 1861 .... Schiel SiC1, :AgCl 2 27-99 39.(( Note on Substitution in the Benzene Nucleus.” By H. Foster Morley. In an addendum to his paper on “An Explanation of the Laws which govern Substitut,ion in the case of Benzenoid Compounds,” Dr. Arm-strong says that the formation of metanitro-derivatives on nitra-tion of the sulphates of dimethylaniline, ethylaniline and ethylpara- toluidine, while aniline and para-ace tyltoluidine produced para- or ortho-derivatives, was due to an increase in the basic pomers of nitrogen consequent on the introduction of hydrocarbon radicles in place of hydrogen. The experiments quoted admit, however, of a different explanation, those substances which are mentioned as giving nieta-derivatives having been nitrated in presence of a, large excess of ice-cold sulphuric acid, the others having been nitrated by a different method.Dr. Armstrong’s hypothesis that meta-substitution is always pre- ceded by combination of the reagent that produces substitution with the radicle already in the benzene nucleus can hardly be maintained in face of such facts as that strong nitric acid converts dimethyl- aniline into a paranitro-derivative. We know nothing concerning the cause of formation of rneta-compounds ; but only that when the group already present is highly chlorous, the new radicle, on entering, takes up the meta-position. 40. ‘‘ Reply to the Foregoing Note.” By Henry E. Armstrong. It is pointed out that Dr. Morley somewhat misrepresents the author’s views. In order to make this clear, the formation of ortho- and para-derivatives is more fully discussed, and an explanation is given of the reasons which led him to think it probable that the behavionr of a compound like dimethylaniline would not in all cases be strictly in accordance with the para-ortho-law.The author con- siders that Dr. Morley’s statement, that “ the group N(S04H)H3in aniline sulphate, &c., is more chlorous than NH2, and hence gives rise to meta-derivatives,” is a mere phrase ; it in no way follows that such is the case, inasmuch as compounds containing the basic radicle NH2,or allied groups, and those containing the chlorous radicles C1, Br, &c., in most respects behave alike. DISCUSSION. Mr. GROVES,referring to the author’s remarks on the action of sulphuric acid on aniline, said that when preparing sulphanilic acid he had been unable to find any intermediate product.Professor MELDOLAsaid that he had repeated many of Nolting and Collins’ experiments, and that his results were entirely confirma- tory of theirs. In preparing sulphanilic acid on a large scale no intermediate compound was formed, according to his experience. Dr. MORLEYsaid that it appeared to him that the cases quoted by Dr. Armstrong did not serve to substantiate his view any more than those previously advanced. Dr. ARMSTRONG,replying to Mr. Groves, said that it was not to be expected that an intermediate product such as he had referred to would be noticed in preparing snlplianilic acid.As regards Dr. Morley’s criticisms, it was most important to elicit opinions on the subject under discussion, and such criticisms were most welcome ; but it was clear tthat Dr. Morley had failed to understand his views. At the next meeting, on May 5th’ the following papers will be read :-“ A Contribution to the Study of Well Waters.” By R. Waring-ton, F.R.S. “ The Influence of Temperature on the Heat of Dissolution of Salts in Water.” By Prof. Tilden, F.R.S. “ Crystals in Basic Slag.” By J. E. Stead and C. H. Ridsdale. ‘‘ The Distribution of Lead in the Brains of two Factory Opera- tives dying snddenly.” By A. Wynter Blyth. HARRISON AND SONS. PliIKTERS Ih’ ORDINARY ‘10I1RE MAJESTY, ST.MARTIN’S UXlI.
ISSN:0369-8718
DOI:10.1039/PL8870300057
出版商:RSC
年代:1887
数据来源: RSC
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