O. W. Richardson. The emission of electricity from hot body (monographs of Physics) London, 1916. (304 pp.)

The study of the emission of electrons by heated bodies has in recent times acquired, in addition to enormous theoretical interest, great practical significance, thanks to the work of Coolidge, who found in the emission of electrons a new method for obtaining cathode rays that produce X-rays.

Richardson’s book, by one of the most prominent workers in this field, may therefore be of interest not only to physicists and chemists, for whom the theoretical investigations are important, but also to engineers and technicians engaged in the construction and improvement of X-ray tubes.

The book contains nine chapters and sets forth successively the general theory of the emission of electrons by heated bodies, the variation of this emission with temperature, the influence of gases on emission, the emission of positive ions by heated metals and the influence of gases on this latter effect, the emission of ions by heated salts, and, finally, ionization and chemical action.

The exposition is distinguished by clarity and precision, and Richardson’s book, issued in the excellent series of monographs published by J. J. Thomson, is a valuable aid in becoming acquainted with this new field of the science of electricity.

P. Lazarev.