58 SECTIONAL ADDRESSES. 
which a suggestion is put forward that the phenomenon of radioactivity 
exhibited by the heavier atoms may be due to some interaction between 
the nuclear and the external electrons in these atoms, he finds that the 
nearest approach of an electron to the nucleus in the atom of uranium 
according to Bohr’s scheme of orbits is 16x 10-* cm. If the electronic 
orbit closest to the nucleus in the atom of uranium had 4 for the value 
of its azimuthal quantum number, it would mean that the shortest 
distance of approach to the nucleus would be equal to4x 107" em. As 
the radius of the nucleus of the atom of uranium has been shown to 
be 6.5x10- em. it is evident that such an orbit could not exist. For 
reasons of this character we are practically precluded from assigning 
to k, the azimuthal quantum number, a value less than 1 in defining the 
electronic orbits in atoms. 
In this paper an attempt has been made to outline some of the 
leading features of the quantum theory as it is being used to solve 
the problems of atomic structure as well as of those connected with the 
origin of radiations emitted by atoms. Other illustrations of special 
interest might have been drawn from the treatment of problems that 
have arisen in a study of band spectra®’ and of fluorescence pheno- 
mena.°? The recent work of Cabrera,°* Epstein,®® and Dauvillier,** on 
paramagnetism, too, has a most interesting connection with the deve- 
lopment of inner systems of electronic orbits in atoms in Bohr’s scheme 
of the genesis of atoms. 
I venture to think, however, that the few iliustrations presented may 
serve, in a measure, to indicate the power and also the beauty of the 
methods being put forward to elucidate the problem of the origin of 
radiation. 
5? Kratzer, Die Naturwissenschaften, vol. 11, Heft 27, p. 577, 1923. 
53 Wranck and Pringsheim, Die Naturwissenschaften, Heft 27, vol. 11, 
July 6, p. 559, 1923. 
‘4 Cabrera, Jl. de Phys., t. 6, p. 443, 1922. 
55 Epstein, Science, vol. lvii., No. 1479, p. 532, 1923. 
*6 Dauvillier, U.R#., June 18, p. 1802, 1923. 
ee 
