Festschriften der Polytechnischen Schule und der Technischen Hochschule Stuttgart: Technische Hochschule Stuttgart. Technisch-wissenschaftliche Prüf- und Beratungsstellen

Bibliografische Daten

Zeitschrift

Persistenter Identifier:: 1562653543533

Titel:: Festschriften der Polytechnischen Schule und der Technischen Hochschule Stuttgart

Strukturtyp:: Zeitschrift

Sammlung:: Zentrale Quellen zur Universitätsgeschichte

Lizenz:: https://creativecommons.org/licenses/by-sa/4.0/

Band

Persistenter Identifier:: 1562653543533_J1939

Titel:: Technische Hochschule Stuttgart. Technisch-wissenschaftliche Prüf- und Beratungsstellen

Jahrgang/Band:: 1939

Erscheinungsjahr:: 1939

Sprache:: und

Strukturtyp:: Band

Standort:: Universitätsarchiv Stuttgart

Signatur:: verschiedene Signaturen

Lizenz:: https://creativecommons.org/licenses/by-sa/4.0/

Sammlung:: Zentrale Quellen zur Universitätsgeschichte

Kapitel

Titel:: A) Institute

Strukturtyp:: Kapitel

Kapitel

Titel:: Laboratorium für Röntgentechnik

Strukturtyp:: Kapitel

CHEMIcAL News: | Origin of the Hydrocarbon Flame Spectrum. 293 There is, however, a spelrum to which we have had occasion to refer in the papers on the spectra of the com- pounds of carbon, which closely resembles that of a com- nound substance, and which we, in common with some other spectroscopists, have been led to attribute to the aydrocarbon acetylene, without, however, being able to ring forward such rigid experimental proofs of its origin as we have adduced mn the case of the three substances above referred to. In other words, the experimental evidence that the hydrocarbon flame spe@rum was really iue to a hydrocarbon was always indire@&. Thus, we showed that many flames containing carbon, such as those of hydrogen mixed with bisulphide of carbon or carbonic oxide, and the flame of cyanogen in air, did not yive this spectrum, and these particular flames are known, Tom the investigations of Berthelot, to be incapable of generating acetylene under conditions producing incom- plete combustion. On the other hand, we found that a lame of hydrogen mixed with chloroform, which easily generates acetylene, gives the hydrocarbon flame spe&rum n a very marked manner, and 1t is known that the ordi- nary blowpipe flame, in which the same spectrum is well developed, contains this hydrocarbon. These and other experiments point to the intimate relation of hydrogen and carbon in the combined form of acetylene to the produéion of this spe@rum during com- oustion. In our various observations on the spe&rum of ‘he ele@ric arc taken in different gases, the flame spec- frum was always noticed, and seemed to be independent of the surrounding atmosphere. In the mode in which those experiments were conducted, it was easily shown that the carbons were never free from hydrogen, and that he gases always contained traces of aqueous vapour. Under these conditions acetylene is formed synthetically Juring the ele@ric discharge, the line spectrum of hydro- zen being absent; so that we were never convinced that the sped@rum was not due to the former substance. It is well to remark in passing, that our previous work on the speGrum of the carbon compounds was mainly directed to that particular spe@rum which is characteristic of the flame of cyanogen, and only indirectly to the flame spectrum of hydrocarbon. We were further supported in connecting the latter spectrum with acetylene, by observing that cyanogen compounds are continuously formed when the arc discharge takes place in gases containing nitrogen, and that in all probability their formation is due, as Ber- ‘helot has shown, to a reaétion taking place between acetylene and nitrogen. Berthelot is positive in his asser- tions that cyanogen is never formed by a direct combina- tion between carbon and nitrogen, and any such apparent combination is due to impure carbon, and the presence of an imperfectly dried gas; in other words, hydrogen is assential to the production of cyanogen under such con- ditions according to the views of Berthelot. Such con- siderations led us to suggest the following view, expressed at the time the experiments were made, as to the origin of the hydrocarbon flame spectrum. “The mere presence of the latter spe@rum feebly jeveloped in the eleéric discharge in compounds of carbon supposed to contain no hydrogen, appears to us to weigh sory little against the series of observations which conne& “his spectrum directly with hydrocarbons.” (Proc. Roy. Soc., vol. 30, p. 160). The arc in the middle of a magnesia crucible often shows no trace of the hydrocarbon set, although the cyanogen are strong. If, however, puffs of air or carbonic acid are passed into the arc. the hydrocarbon lines are produced.” " “When the hydrocarbon spectrum is strong the brilliancy and number of the cyanogen groups that are visible are undoubtedly increased, so that the one variety of vibrations seems to affect the other. This is easily accounted for by the chemical interaction which takes lace between acetylene, nitrogen, and hydrocyanic acid, The hydrocarbon spectrum is brought out at once in the magnesia crucibles by moistening one. of the poles. All THE CHEMICAL NEWS. Vor. XLVI. Wo. 1203. ON THE ORIGIN OF THE HYDROCARBON FLAME SPECTRUM.* By G. D. LIVEING, M.A, F.R.S,, Professor of Chemistry, and J. DEWAR, M.A, F.R.S,, Jacksonian Professor, University of Cambridge. IN previous communications} to the Society we have described the spe@ra of what we believe to be three com- pound substances, viz., cyanogen, magnesium-hydrogen, and water. In these investigations our chief aim has been to ascer- tain fads, and to avoid as far as possible adopting any special theory regarding the genesis of the spe&ra in question. Thus, in speaking cf the magnesium-hydrogen spe@rum, which consists of three sets of flutings closely resembling in chara&ter the flame spedtrum of hydro- carbons, we remark :—* We have been careful to ascribe this line and its attendant series to a mixture of magne- sium and hydrogen rather than to a chemical compound, because this expresses the fads, and we have not yet obtained any independent evidence of the existence of any chemical compound of those elements.” In dealing with the cyanogen spe&trum, we sometimes refer to it as the * nitro-carbon spectrum,” in order to convey that ‘‘we are dealing with a spectrum invariably associated with the presence of nitrogen and carbon, in such conditions that chemical union takes place.” Finally, in summing up our observations on the spectrum of water, we remark ;—* In writing of this and other spe@ra which we have traced to be due to compounds, we abstain from speculating upon the particular mole- cular condition or stage of combination or decomposition which may give rise to such speéra.” The difficulties we have met with in endeavouring ex- haustively to clear up many apparently simple speéro- scopic problems, on a basis of fa& as opposed to theory, is further illustrated in the concluding remarks of our paper entitled * Investigations on the Spe@trum of Mag- nesium,” wherein the following passage occurs :—* The chemical atoms of magnesium are either themselves capable of taking up a great variety of vibrations, or are capable by mutual a&ion on each other, or on particles of matter of other kind, of giving rise to a great variety of vibrations of the luminiferous ether; and to trace satis- fa&orily the precise connection between the occurrence of the various vibrations and the circumstances under which they occur, will require yet an extended series of observa- tions.” (Proc. Roy. Soc., vol. 32, p. 203). Specific speétrahave been satisfactorily proved to emanate from the compound molecules of cyanogen, water, and mag- nesium-hydrogen, so far as we can interpret in the sim- plest way the many observations previously detailed. The fac that a fluted spe@rum is produced under certain con- ditions, by a substance which does not give such a spec: trum under other conditions, is of itself a proof that the body has either passed into an isomeric state or has formed some new compound ; but we are not entitled to assert, without investigation, which of these two reason- able explanations of the phenomena is the true one.

Zugriffsbeschränkung

Nutzungslizenz

fullscreen: Chemical news and Journal of physical science (Volume 46, 1882 (July - December))

Zeitschrift

Band

Kapitel

Kapitel

Inhalt

Downloads

Ganzer Datensatz

Diese Seite

Bildfragment

Formate und Verlinkungen

Formate

Links

Zitieren

Ganzer Datensatz

Diese Seite

Zitierempfehlung