On the absorption spectra of cobalt salts

The following investigation was commenced at the suggestion, and indeed in conjunction with, Mr. Lockyer. Other work, however, prevented his continuing with me this research, but I am much indebted to him not only for instruction in methods of spectroscopic observation, but also for important suggestions and much aid in the course of the work. The more immediate object of the investigation was to examine carefully and systematically the absorption spectra produced by certain coloured liquids and solids, in order to identify the spectra with the substances producing them. If this ,be fully done, a powerful means has been obtained for investigating the changes, be they either chemical or physical, which occur more especially in cases of solution. Of all coloured substances the cobalt salts seemed most suitable for commencing the investigation with, as they give well marked band spectra, and are salts well known and easily obtained.