. The principles of chemistry . , AND LITHIUM 571 common salt be introduced into the flame of a gas-burner, a portion ofit is decomposed, first forming, in all probability, with water, hydro-chloric acid and sodium hydroxide, and the latter then becoming partiallydecomposed by the hydrocarbons, giving metallic sodium, whose incan-descent vapour emits light of a definite refrangibility. This conclusionis arrived at from the following experiment :—If hydrochloric acid gasbe introduced into a flame coloured by sodium it is observed that thesodium spectrum disappears, owing to the fact that metall
. The principles of chemistry . , AND LITHIUM 571 common salt be introduced into the flame of a gas-burner, a portion ofit is decomposed, first forming, in all probability, with water, hydro-chloric acid and sodium hydroxide, and the latter then becoming partiallydecomposed by the hydrocarbons, giving metallic sodium, whose incan-descent vapour emits light of a definite refrangibility. This conclusionis arrived at from the following experiment :—If hydrochloric acid gasbe introduced into a flame coloured by sodium it is observed that thesodium spectrum disappears, owing to the fact that metallic sodiumcannot remain in the flame in the presence of an excess of hydrochloricacid. The same thing takes place on the addition of sal-ammoniac,which in the heat of the flame gives hydrochloric acid. If a porcelaintube containing sodium chloride (or sodium hydroxide or carbonate), andclosed at both ends by glass plates, be so powerfully heated that thesalt volatilises, then the sodium sj)ectrum is not observable ; but if the. Fig. 75.—Bright spectra of copper compounds. salt be replaced by sodium, then either the bright line or the absorp-tion spectra is obtained, according to vdiether the light emitted by theincandescent vapour be observed, or light passing through thetube. Thus the above spectrum is not given by sodium chloride orother sodium compound, but is proper to the metal sodium itself. ThisIS also the case with other analogous metals. The chlorides and otherhalogen compounds of barium, calcium, copper, ttc, give independentspectra which differ from those of the metals. If barium chloride beintroduced into a flame, it gives a mixed spectrum belonging to metallicbarium and barium chloride. If besides barium chloride, hydrochloricacid or sal-ammoniac be introduced into the flame, then the spectrumof the metal disappears, and that of the chloride remains, which differsdistinctly from the spectrum of barium fluoride, barium bromide, orbarium iodide. A certain common r
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Keywords: ., bookcentury1800, bookdecade1890, bookpublis, booksubjectchemistry
