NEFT BOOKS T h e M e c h a n i s m o j Contact Catalysis. By R. H. GRIFFITH. 208 pp. Oxford University Press, 1936. Price: $5.00. The author presents the theoretical rather than the technical aspects of catalysis, in full recognition, however, of the fact t h a t contact catalysis is still largely in the empirical stage. While much progress has been made in correlating the fields, prediction still rests on analogy, and trial and testing remain the principal guides. The development of the subject is presented in a logical order with ample citations of the most important literature. The eight chapters deal with experimental methods, adsorption, promoters and carriers, poisoning and retardation, examination and geometry of the catalyst surface, mechanism of catalysis and development of catalysts. The monograph closes with an interesting discussion of the direction in which future progress is most likely to be made. S . C. LISD. Metastrukturen der Materie. By WOLFGASG OSTWALD.23.3 x 16 cm.; 17 pp. Dresden and Leipzig: Theodor Steinkopff. Price: 0.80 R l I . This little book is a reprint of a lecture delivered by the author in 1935, and contains a survey and classification of material entities of colloidal dimensions, i.e., dimensions lying between ordinary molecular sizes and the wave lengths of visible light. These the author calls “metastructures.” The brochure is intended t o convey t o a non-specialist audience a clear idea of the JTorld of material entities which constitutes the special field of study of colloid science. F. G. DOXNAN. Schwimmaufbereitung. By W. PETERSES.22 x 15 cm.; xii and 337 pp. Dresden and Leipzig: Theodor Steinkopff, 1936. Price: 18 RN. This book, which forms Volume 36 of the Wissenschaftliche Forschungsberichte (Saturwissenschaftliche Reihe) edited by Dr. R. E. Liesegang, gives a valuable account of the theory and practice of the separation of solid particles of different sorts by means of differential flotation. As is x-ell knoxn, this flotation method of concentrating and separating the valuable constituents in ores is of enormous importance i n mining and smelting. The main divisions of the vork are as follows: (A) Introduction; (B) Flotation Apparatus; (C) Theory of Flotation; (D) Flotation Substances; (E) Flotation Concentration of Ores. There are given many practical examples, a comprehensive bibliography, and good author and subject indexes. The book can be heartily recommended. F. G. DONNAN. Suinerical Data o n Rotatory Power. By E. DARMOIS.23 x 28.5 cm.; 68 pp. Paris: Gauthier-Villars, 1936; llcGraw-Hill Book Co., Agents. This fasciculus is a n advance reprint from Volume S I of the A n n u a l Tables o j Constants and Numerical Data, published under the auspices of the International Council of Scientific Cnions and of the International Union of Pure and iipplied Chemistry by a n International Committee with X. Thon as Editor-in-Chief. 507
