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NEW BOOKS The Anodic Ozidation of Aluminum and its Alloys. By A. JENNY.Translated by Winifred Lewis. 6 x 9 in.; vi 231 pp.; 107 figures; 36 tables. New York: The Chemical Publishing Company, Inc., 1940. Price: $6.50. The anode reactions of aluminum have been studied more extensively and in greater detail than those of any other single metal. Dr. Jenny has packed into this small volume some of the pertinent facts relating to the commercial processes which make use of the reactions taking place a t an aluminum anode. Starting with simple electrochemistry and the chemical properties of aluminum, the author builds a foundation for his discussion of valve action and the formation of the condenser type of film. Then follows a description of the production and properties of the thick anodic oxide films which are used commercially for their protective and decorative properties. All the steps employed in the production of anodic oxide coatings are discussed to some extent, such as preliminary surface treatment and after-treatments which include sealing, dyeing, and impregnation with photosensitive compounds. After weighing the good and bad features presented for each electrolyte and the coatings produced therein, one wonders why so much space was devoted to the operating characteristics of the oxalic acid electrolyte and so little space given to the sulfuric acid electrolyte, which is the one with the greatest commercial usage. Lewis has given us a good translation of the original German text. In only a few instances does the English translation differ from the German. The translator has added four or five footnotes to increase the single literature reference included in the original German text to the number of three or four in the translation. Unfortunately, most of the references in the text give the name of the author only and the reader must himself search for the source of publication. I n a number of instances, data from the unpublished work of Siemens and Halske A. G. are included. A list of British patents dealing with oxide coatings on aluminum has been added to the translation, but the reference to British and American developments in the text is scarcely commensurate with the pioneering part they have played in this art. For the most part, the book is easy to read and has many interesting observations not found elsewhere. I t has been written more from the practical than the theoretical standpoint and is recommended to those interested in the commercial production of aluminum oxide coatings. R. B. MASON.
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Waves. By C. A. COULSON.5 x 71 in.; viii 156 pp.; 29 figures. London: Oliver and Boyd, 1941. New York: Interscience Publishers, Inc., 1941. Price: $1.50. This little book, which is one of the series of University Mathematical Texts, gives a concise account of the common types of nave motion. Starting with the fundamental equation of wave motion, as many problems as possible are discussed: waves on strings, waves in membranes, waves in bars and springs, waves in liquids, sound waves, and electrical waves. While all of these topics have been discussed by theoretical physicists many times, still the present compilation is noteworthy for its clarity of presentation and i t s conciseness. GEO. GLOCKLER. Grundlagen und Ergebnisse der Ultraschalljorschung. By E ~ O HIEDEMANB. N 61 x 91 in.; ix f 287 pp.; 232 figures; 1 color plate. Berlin: Walter de Gruyter and Co., 1939. Price: 24 RM. (about 88.50). This book presents by far the most thorough and complete review of the whole
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realm of ultrasonics. Written by one of the foremost investigators in the field, the subject matter is competently treated in an unusually unbiased manner. The text of the book is divided in four parts, preceded by a short historical introduction. I. The production of ultrasonics: (1) the piezoelectric sound generators; (2) the magnetostrictive sound generators; (3) the air-jet oscillator of Hartmann and other generators of ultrasonics. 11. Methods of investigating the sonic field: (1) mechanical methods; (2) optical methods; ultrasonic waves as optical gratings; (3) absorption measurements. 111. Propagation of ultrasonics: (1) propagation in media of large dimensions; (2) propagation in media of small dimensions, some practically important cases; (3) velocity of propagation and absorption; (4) determination of the elastic constants of solid bodies. IV. Effects and technical applications of ultraaonics: (1) physicochemical effects; (2) biological effects; (3) preparation of disperse systems; (4) aerosols in the sonic field; ( 5 ) testing and improving of materials; (6) modulation of light; (7) under-water sound technique (marine application), In addition there are twenty-two tables, an extremely useful bibliography enumerating more than thirteen hundred references (giving the full title of each paper), a classification of the literature according to subject matter, and a n adequate subject index. High-pitched sound waves, in addition to comprising an interesting field in themselves, are of particular interest to the physicochemist, as they offer newtools to gain an insight into many diversified problems. Foremost among them is the investigation of themolecular structure of liquids and of the elastic properties of solids, particularly crystals. In colloid science and biology, ultrasonics have likewise been successfully employed as a research tool. By far the most successful application of ultrasonics to date is their marine application: under-water signalling, sounding of depths, and the location of submerged objects. This latter problem actually resulted in the modern development of the field after the disastrous collision of the illfated steamship Titanic with an iceberg. The precipitation of fogs and smokes by high-pitched sound is currently being tested on a technical scale by several groups of investigators. Another promising application is the modulation of light, which is likely to become important in television. Testing of materials for imperfections and the preparation of disperse systems by ultrasound may one day also be developed into practical methods. The same holds true for their medical application. The use of small type in much of the book has enabled the publishers to compress a very large amount of material into a relatively small space. The numerous figures are excellently selected and very instructive. One should not incriminate the author for omitting extensive references t o the patent literature. The reviewer knows from his own experience that the patent literature contains any number of misleading claims. Anyone interested in an extensive review of ultrasonics, pure as well as applied, will profit considerably by reading Dr. Hiedemann’s book. It is indispensable for those actively engaged in any branch of research on high-frequency sound waves.
K ~ R SOLLNER. L
