The absorption spectra of mixed metallic vapours.—II. The spectra of volatile compounds of magnesium and the alkali metals

Abstract

In a previous communication (‘ Roy. Soc. Proc.,’ A, vol. 105, p. 221 (1924) a band system has been described which is found only in the absorption spectrum of the mixed vapours of sodium and potassium. It was suggested in explanation of this observation that molecules of a volatile compound of the two metals must be present in such mixtures; a supposition which H. G. Smith has since confirmed by comparison of the fine structure of these bands with that of the normal sodium and potassium band spectra (‘ Roy. Soc. Proc.,’ A, vol. 106, p. 400 (1924) ). Bands probably analogous in origin have now been found in the absorption spectra of mixtures of the vapours of magnesium and alkali metals. Two of these spectra —which may be called the “magnesium-sodium” and the “magnesium-potassium” bands —were recorded many years ago by Liveing and Dewar (‘ Roy. Soc. Proc.,’ vol. 27, p. 350 (1878), and ‘Collected Papers,’ p. 13), but appear to have attracted no subsequent attention. This early description has been amplified, and corresponding absorptions have been shown to exist in mixtures of magnesium with rubidium and cæsium.