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If “degree” of surface roughness is to be accepted as referring to the average height of elevations, as revealed by a profile, then for Dr. Bikerman’s “type” of surface roughness, which is a vague term, one should use the surface roughness factor. This is a precisely defined quantity. A better name perhaps would be the “roughness area ratio.” No satisfactory general method of arriving at a numerical value for the roughness area ratio of a rough surface from analysis of profiles, taken at right angles or in any other way, is readily apparent. Gas adsorption technics for measurement of total area would appear to be the only applicable tool. ROBERTN. WENZEL. Westinghouse Research Laboratories East Pittsburgh, Pennsylvania October 25, 1949
NEW BOOKS Surface Active Agents. By ANTHONY M . SCHWARTZ AND JAMES W. PERRY. 579 pp.; 5 tables. New York: Interscience Publishers, Inc., 1949. Price: $10.00. The authors of this book have attempted “to present a well-integrated picture of the present state of development of surface active agents”and in this they have been successful. Hundreds of different commercial surface-active agents are known today and are used in a diversity of applications. This is surprising when one considers that practically the entire development of these materials has occurred within the last three decades. The surfaceactive agents have been classified by the authors as follows: I. Anionic, 11. Cationic, 111. Non-ionic, IV. Ampholytic, V. Water-insoluble emulsifying agents, and VI. Substances that are surface active in non-aqueous solutions. The book is divided into three parts: Part I deals with “Processes for Synthesizing and Manufacturing Surface Active Agents.” Methods for laboratory synthesis and for commercial production are carefully disclosed. Part I1 deals with the “Physical Chemistry of Surface Active Agents in Theory and Practice.” Fundamental theories underlying the effects of these materials are given detailed treatment. Some of the physical properties of the solutions such as wetting and spreading, film formation, osmotic pressure, electrical properties, dispersion, deflocculation, and suspending action as well as foaming, emulsification, and detergency, have been given special consideration. P a r t I11 deals with “Practical Applications of Surface Active Agents.’’ This part is well done and makes interesting reading, inasmuch as i t clearly emphasizes the very wide scope of application of wetting agents. The principal topics treated under this heading are applications to: the textile industry; cosmetics and personal use; pharmaceutical, germicidal, fungicidal, and disinfectant uses; household, laundering, dry cleaning and general use; metal technology; paints, lacquers, inks, and pigments; leather technology; petroleum and lubrication; ore flotation; other industries utilizing a variety of surface-active agents; and miscellaneous uses. Of particular value are the 1553 literature references. There is no question that this book is the most complete one dealing with this new, important, and rapidly developing subject. It is well organized and the material is clearly presented. The book would constitute a valuable addition to any chemistry library. F. E. BARTELL.
