Excerpt from The Absorption Spectra of Solutions, of Comparatively Rare Salts: Including Those of Gadolinium, Dysprosium, and Samarium, the Spectrophotography of Certain Chemical Reactions and the Effect of High Temperature on the Absorption Spectra, of Non-Aqueous SolutionsDuring the last decade a considerable number of physicists have directed their efforts towards solving some of the many problems of spectroscopy. The following chapter will contain a discussion of some of this work, with the view of recording part of our experimental knowledge concerning the nature of the emission and absorption centers of light, the connection between these centers and molecular and atomic structures, the effect of ionization and recombina tion on these centers, and the effects and changes that can be produced by physical and chemical agents such as temperature, the presence of a mag netic field, etc., upon the constitution of the emission and absorption centers.Emission and absorption centers will be defined as the smallest particles from which we can obtain characteristic absorption or emission spectra. A further division of the centers of any characteristic spectrum would make it impossible to obtain that spectrum, though the resultant particles may possess characteristic absorption or emission spectra of their own. When emission or absorption centers move with reference to an observer, the frequencies of the spectral lines and bands will show the Doppler effect.About the PublisherForgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.comThis book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully, any imperfections that remain are intentionally left to preserve the state of such historical works.