A brief account is given of the classical electron theory of anomalous
dispersion and line absorption. The oscillator strength, or f-value,
is introduced as the factor involved in taking over the results
of classical theory in a modern quantum mechanical formulation. The
relation between f-values and the transition probabilities of Einstein
is derived.
A summary of methods for experimental determination of f-values for
atomic transitions is given, and in particular the method of total absorption
is considered in detail. The equivalent width or total absorption
of an absorption line is defined, and the relation of this to the oscillator
strength of the line, the so-called curve of growth, qualitatively
explained.
The laboratory apparatus used in the present investigation is described
in detail, as are the methods of obtaining and reducing the experimental
data.
An account is given of unsuccessful experiments on the resonance lines
of Ca. Absolute nf-values obtained for three lines of Cr are reported, and
on the basis of unsatisfactory vapor pressure data, tentative absolute
f-values for these lines are assigned. Absolute f-values for three lines
of the Ni spectrum are reported, the vapor pressure data for Ni being
reliable. A conversion factor is obtained by which the relative gf-values
for Ni given by King may be reduced to an absolute scale.</p