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given in good number and often “one picture says more than many words”. The first historical chapter contains a series of little-known and interesting facts. Naturally opinions will differ as to the material that should be included in a book having this goal; the reviewer would miss gladly a good deal of the systematics brought in in the first chapters and would prefer to find, instead, in later ones more about solvation, coacervation, colloidal electrolytes, and Liesegang’s rings. But the material chosen by Hauser is suitable for informing the reader a# to the scope, the problems, the methods, and the results of colloid science. The author avoids mathematical reasoning in the seventeen chapters, i.e., in two hundred and twenty-six pages of the book; he adds, however, an appendix of forty-six pages, containing a detailed mathematical discussion of some important colloidal problems. A certain preponderance given to the applications of optics and x-rays in colloidal physics is justified by their great significance. H. FREUNDLICH. First Report on Viscoszty and Plasticzty. Prepared by the Committee for the Study of Viscosity of the Academy of Sciences a t Amsterdam. Second edition, 7 t x 10: in., viii 272 pp.; 98 figures. New York: Nordemann Publishing Company, Inc. Price: $7.00. The First Edition of this First Report on Viscosity and Plasticity was reviewed briefly, together with the Second Report, a short time ago (J. Phys. Chem. 42, 1249 (1938)). The fact that the second edition has been published after only four years proves how welcome this sound and extensive treatment of viscosity and plasticity has been to many readers. The chapters particularly interesting t o the physical chemist are the first and second ones by J. M. Burgers, entitled “Mechanical Considerations-Model Systems-Phenomenological Theories of Relaxation and Viscosity” and “Remarks in Connection with the Experimental Investigation of Flow Properties”; the third one, by H. G . Bungenberg de Jong, entitled “Viscosity hfeasurements with Special Reference to their Application in Colloid Chemistry”; the fourth one, by C. J. van G e u wenburg, entitled “Viscosity and Plasticity from a Technical Point of View.” The title of the third chapter might be misunderstood; i t treats only the true, Newtonian viscosity of colloidal solutions, not their anomalous or structural viscosity. Anomalous viscosity has so far not been dealt with comprehensively in these reports, although many factors connected with it, e.g., yield value, plastometers, and the motion of small elongated particles in viscous liquids have been discussed in other chapters, for instance, in chapters I and IV of this First Report and in chapters 111, IV, and V of the Second Report. Nevertheless, a special treatment of these phenomena, particularly as t o their importance in colloid science, would be desirable. The book under review is mainly an impression of the first edition. Minor changes are an interesting insertion in H. J. Jordan’s chapter (“Viscosity Effects in Living Protoplasm”) and an index.
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H. FREUNDLICH. Protective Coatings for Metals. By R. M. BURNSAND A. E. SCHUH. American Chemical Society Monograph No. 79. 407 pp,; 46 tables; 89 figures. New York: The Reinhold Publishing Corporation, 1939. Price: $6.50. This book is in a sense a revision of the monograph by H. S. Rawdon, published in 1927, but is enlarged to include protective coatings of all types, including paints and lacquers. The subject matter of the book has been well selected, and throughout there is evidenced the thorough familiarity of the authorities with the methods of preparing
