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wicklung des Tonfilmverfahrens der AEG; (2) Verbesserungen des Zeitdehners und Anwendung in der Aufnahmepraxis; (3) Zur Elektrotechnik der Entladungsgefasse; (4) Zur Physik der Entladungsgefasse; (5) Gaskonzentrierte Elektronenstrahlen und ihre Anwendung; (6) Geometrische Elektronenoptik; (7) Mitarbeit der AEG an der Nordlichtforschung; (8) Untersuchungen uber das Wesen des Elektrons; (9) Wirkung neutrales Gasmolekule gegenuber langsamen Elektronen und langsamen Protonen; (10) n b e r die physikalischen Grundlagen der Ionentherapie; (11) Neuartige Werkstoffe fur Pupinspulen; (12) Einzelarbeiten des metallurgisch-magnetischen Laboratoriums; (13) Neue magnetische Messmethoden; (14) Beitrage zur Physik der Nitrobenzol Kerrzelle; (15) uber lichtelektrische Alkalizellen. This table of contents will serve to give some notion of the very varied fare presented, and those interested in any special subject can judge whether any topic of importance to them is discussed in this volume. It is hardly necessary to say that the subjects are handled in a very thorough and interesting fashion, and the volume, both in content and in the matter of mechanical production, is a worthy record of very important work. ALLANFERGUSON.
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Moleculur Rays. By RONALD G. FRASER. xii 204 pp.; 78 figs. Cambridge University Press. New York: The MacMillan Company. This book is one of the Cambridge series of physical chemistry under the editorship of E. K. Rideal. The book is of the sort that the English seem to do unusually well, being an account of the technical methods and state of progress in research involving the molecular ray technique. The author spent some time in Stern’s laboratory at Hamburg and is qualified by training and experience to write such a manual. He naturally gives a great deal of prominence to the Hamburg laboratory and very properly so, since the molecular ray technique was originated by Professor Stern and its most important applications have been made by him. The consideration given to work along this line in American laboratories is all that could be expected from a book Gritten on the other side of the water. The trend of recent events indicates that polecular ray research may become peculiarly an American institution. The only c!efec’t to be noted in the book is the lack of a bibliography. W. H. RODEBUSH. Some Physical Properties of the Cocalent Link in Chemistry. By NEVIL VINCENT SID(:WICK. 23 x 15 em.; 249 pp. Ithaca, New York: Cornell University Press, 1933. Price: $2.00. The volume under consideration is based upon a series of lectures given at Cornell University by the author while he held the George Fisher Baker Non-resident Lectureship during the second semester of 1930-1931. Owing t o the high degree of specialization in chemistry, i t is rare t o find a chemist who has succeeded in achieving a comprehensive grasp of the science as a whole. Professor Sidgwick is one of the most distinguished of these few. I n the present work he has brought together bits of information gathered from the most diverse sources and has interpreted them with reference to their bearing on our conception of the nature of the covalent bond. The result constitutes a classic treatise-the purpose of which is expressed by the author in the following characteristically modest fashion. “The book is an attempt to set out the methods of measurement of some of the more important properties of non-ionized links, and to discuss the results so far obtained.” “I have tried to include the more important researches bearing on these questions which have appeared up t o the summer of 1932, and a few later ones of special interest.”
