Quantenmechanik der Materie und Strahlung, bearb. v. G. BECK, F. BLOCH, P. DEBYE, 2 Aufl., T. 2, Lpz. Akademische Verlagsges. Moleküle, 1932, 604 S. (Handbuch d. Radiologie, Bd 6). Quantum Mechanics of Matter and Radiation

The volume under review contains a series of survey reports united by a common aim: to show what methods modern physics has developed for the study of the structure and physical properties of molecules.

The principal source of our information about molecules is band spectra. The first article, by Kronig, gives a brief survey of the theory of band spectra and of its application to the question of the structure of molecules. The exposition is extremely compressed and amounts, to a considerable degree, to a scholarly summary of a more extensive monograph by the author on the same subject. The article may be useful to a specialist working in an adjacent field of physics for reference, but it is of no use to a reader little acquainted with this field.

The second article, by Debye and Sack, is devoted to the electrical structure of molecules. A considerable part of the material repeats Debye’s book on polar molecules, although it is considerably broader than it. The Kerr effect and its application to the structure of molecules are excellently presented. The mastery of exposition which Debye possesses to perfection makes the article an excellent aid even for the non-specialist; the same cannot be said of the other articles in the volume.

In the third article, Plaček has for the first time systematized everything that has hitherto been done (mainly by him himself) on the application of the theory of combi-

national scattering to questions of molecular structure. Much appears in print for the first time, and only with the appearance of this work does it become possible to study molecules by means of Raman spectra.

Placzek’s article is certainly difficult even for a specialist and requires serious study. Especially valuable are the tables included in it, which facilitate the systematization of spectra.

In the fourth article F. Bloch gives a survey of the magnetic properties of molecules. The article is favorably characterized by the author’s deeply physical approach to the problem. As regards the calculation presented, the author seeks to clarify the physical essence of the assumptions made in order to simplify the problem, to indicate the limits within which this assumption is possible, and to compare the results of quantum theory with classical ideas.

Somewhat departing from the plan of the volume devoted to molecules, F. Bloch also gives a brief survey of the theory of ferromagnetism. This concluding part of Bloch’s article cannot be considered successful. For the specialist it gives very little; for the nonspecialist it is uninteresting and useless.

The last article by V. Heitler is devoted to the theory of the chemical bond. Since the reviewer himself took a close part in the creation of the theory presented, he is in a difficult position in giving his opinion of Heitler’s article. It is possible that for the nonspecialist it is too specialized and presupposes too solid a knowledge of the foundations of quantum mechanics. Moreover, only the theory of spin valence is set forth fully (the Göttingen school). As regards the question of ordinary valence (Slater, Pauling) and the molecular theory of the chemical bond (Hund, Herzberg), they are only partially touched upon, which distorts the general theory of the chemical bond.

The articles by Placzek and Heitler, to my knowledge, have been translated and are being prepared for publication in Ukraine. The article by Debye and Sack would be extremely desirable and necessary to translate. Bloch’s article, with the necessary additions in the field of ferromagnetism, would likewise be desirable to have in Russian. After all, up to now we still have nothing on the modern theory of magnetism.

Yu. Rumer