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Hydroxyde und Oxydhydrate. By K.FRICKE and G. F. H ~ T T I Gwith , the cooperatioil of H . Zocher and H . Saechtling. 630 pp. Leipzig: Akademische F‘erlagsgesellschaft, m.b.H., 1937. This volume constitutes P a r t 1X of the Handbicch der ullgeir~el‘nenC h e m i e edited by Paul Walden. Every worker interested in the physical and chemical properties of oxides, hydroxides, and their hydrous products will welcome the publication of this monograph. The literature in this field is extremely extensive and full of contradictory statements. Fricke and Huttig, both of whom have contributed so much t o the subject, have succeeded in n-riting a critical and systematic review with full consideration of the world literature. Particular emphasis is laid on the structural relationships betxeen, and physicochemical properties of, the metal oxides, hydroxides, and hydrous products. S o t all the properties are discussed in an exhaustive ”ay, but a multitude of references to the literature, Gmelin Kraut, and, regarding the colloid chemical properties, to Weiser’s T h e Hydrous Oxides and Hydroxides enable the reader to find more complete sources of information. The book is divided into a special part (602 pages) and a general part. I n the former the properties of the individual metal oxides and hydroxides are given, including a highly successful chapter on the system Si02-H20by Zocher of almost 100 pages, and a chapter on the rare earths and the platinum metals by Saechtling and Zocher. The general part comprises chapters on x-ray analysis with detailed discussion regarding the perfection of the crystal lattices, aging (unfortunately, not much has been said about thermal treatment, although a summary of Hiittig’s own Ivork would have been very valuable), aqueous vapor pressure, kinetics of dehydration, thermochemical d a t a showing the different energy contents of oxides and hydroxides as a function of the degree of perfection of the lattices, magnetic susceptibility, and dielectric constants. The book will be of great use in defining a compound as an oxide hydrate, hydrous oxide, hydroxide, hydroxide hydrate, or hydrous hydroxide. The detailed table of contents with the subject and author index are helpful in finding the wealth of information offered in this book. The print and appearance are excellent. Chemists owe a debt of gratitude to the authors for their painstaking work of collecting all the important data on this subject into one volume. I. 11. KOLTHOFF.
Relaticity Theory o j Protons and Electrons. By A. S.EDDINGTOX. This unusual book contains a review and “summing up” of the theory which Professor Eddiiigton has been developing for the last several years in an effort to bridge the gap between the theory of relativity and quantum mechanics. I n reviewing a book of this type, in which there is such a departure from customary theory and notation, i t is only possible to sketch the highlights of what the reader may expect t o find there. This is not a textbook, either of relativity theory or of quantum mechanics. Consequently the reader must be already well grounded in both of the theories arid their associated mathematics, and must expect that the main emphasis will be on the author’s ideas about their relationships. K i t h this n-ord of warning, we may turn to a brief discussion of the book itself. The first portion is devoted to the study of the complete set of sixteen anticommuting operators built up from the four Dirac operators as basis. This leads to the introduction of a 16-space and of :I calculus of vectors and tensors in this space. This forms the first part of the mathematical bridge between relativity and quantum mechanics. .4psrt froin this puwly xnat1icinatir:il throry the most iiiteresting portions of the
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hook are the discussions of the author’s idras on the composition of tn-o or more simple systems t o form a complex system, the Pauli exclusion principle. and the sharp distinction betneen “internal” and “external” \\ave functions These must be studied t o understand the basis for the startling results nhich the authoi has predicted from his theory: the value of 1/137 for the fine structure constant, the mass ratio of thc proton and electron, ctc The sophisticated reader will undoubtedly find here man! things n i t h n h i c h he nil1 n a n t t o disagree. h u t the reviener believes t h a t if he approachrs the theory a t all sympathetically he vi11 also find much that is stimulating and provocative of further thought. E 1, HILL A p p l z e d C h e m i s t r y j o r Engineers By A F. I3 W ~ R D 19 Y 12 cm ; XI and 127 pp. London: Longmans, Green and Co , 1936 Price. 5s The writing of an easily understandable book on applied chcmistry for engineers is n o rasv task. The present hook is intended, the author tells us in his preface, t o provide a practical course in applied chemistry for students of mechanical, municipal, or electrical engineering in technical colleges and universities. As an alternative, its use is suggested t o students of pure chemistry needing an introduction t o applied chemistry. The book may appeal more t o the latter The method of instruction adopted is theoretical description follov ed by experiment t o be performed; general references t o textbooks or pamphlets a r e added at the end of each part. Almost half the volume is allotted t o water, domestic and industrial, its analysis and treatment. This branch of the subject is dealt mith in detail; alternative and latest methods are given with, in some cases, literature references. The difficult problem of metal corrosion, including a consideration of overvoltage and the passive state, occupies the next thirty-odd pages, the elertrorhemical theory only of corrosion being considered. The rest of the text of the volume is concerned n i t h coal and oil. I n contrast t o the section on iTater, the information is scanty, in the case of coal only proximate analysis being mentioned, and no calorific determination in the case either of coal or of oil. Some mistakes occur, for instance, an obvious misprint in the equation on p. 56, the high value of the Faraday (p. 73), and the description of methyl orange as a a e a k acid indicator (p. 116). Honever, the book as a whole serves a useful purpose. and a future edition might be extended with advantage. W. H . PATTERSON.
Elektronentheorie der Metalle. By H . FROHLICH. 22 x 14 cm. ; vii and 386 pp. Berlin : Julius Springer, 1936. Price: 27 RM.; cloth-covered, 28.80 RAf. Dr. Frohlich gives a n exhaustive and detailed account of the modern electron theory of metals. T h e mathematical physicist nil1 find the hook full of useful information; in particular the chapters on the optical properties of metals are n o r t h mentioning. This group of problems, t o which the author himself made valuable contributions, is particularly clearly exposed. T h e book appeals also t o experimentalists who want t o acquaint themselves n i t h the theory, and only the elements of wave mechanics are assumed t o be knoivn t o the reader. But Dr. Frohlich wmts the full attention of his reader, and a superficial glance a t the book may n o t lead t o much benefit. This holds particularly for an English reader. n ho may he scared by the double difficulty of rather involved German constructions expressing involved arguments n ith many afterthoughts H e will, hov ever, he rev arded for his patience b y much interesting information, and a very detailed list of references opens the w a y for further studies The book represents a fair summary of the present position.
