On the Bunsen flame spectra of metallic vapours

In seeking to solve the problem of the structure of atoms, especially of the more complex ones, it is of great important to know what are the simplest or fundamental spectra which such atoms are capable of emitting. Information regarding such fundamental frequencies for the atoms of some metals has been obtained from investigating the characteristics of both the absorption and emission spectra of vapours of these metals. For example, McLennan and Edwards have shown that, with the non-luminous vapours of mercury, zinc and cadmium, narrow absorption bands are obtained, using moderate vapour densities, with lines whose frequencies are given byv = (1.5 , S) – (2,p 2 ), andv =(1.5, S) – (2, P). The first of these is the frequency of the first member of Paschen's combination seriesv = (2,p 2 ) - (m , S), and the second is the first member of the singlet seriesv = (1.5, S) - (m , P). Moreover, one of us has also more recently shown from absorption experiments that for magnesium atoms the frequenciesv = (1.5, S) - (2, P),v = (1.5, S) - (3, P), and possibly also those of still higher members of the seriesv = (1.5, S) - (m , P) are the fundamental ones. with this metal the frequencyv = (1.5, S) - (2,p 2 ), does not appear from experimental evidence as yet available to be fundamental.