Absorption Spectra of Nitrates the region 300

Abstract

Extensive observations have been made by various workers on the absorption of ultra-violet light by solutions of the metallic nitrates. The results suffered from the disadvantage of being qualitative or semi-qualitative only, and the interpretations offered could not compel assent. Recent work has tended to increase confidence in the validity of certain methods claiming to yield quantitative data. An opportunity is thus afforded for a closer investigation of the less pronounced changes in light absorption brought about by variations in the environment of absorbing ions or molecules. The necessity for such an enquiry was indicated by von Halban* in the words “ systematic investigations of the influence of other substances on the extinction coefficient are scarcely extant.” The following conditions must be satisfied if work of this nature is to be of value :— i. The methods used must be reliable. ii. The substances must show a well defined absorption band due to some common entity, they must be readily purified, a long series of related compounds must be available and some at least must be soluble in solvents other than water.