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predicting experimental results. I n harmony with this is the fact that the author evidently does not require his readers to possess mathematical knowledge beyond algebra and analytic geometry. I n spite of the importance of the subject in connection with the measurement of conductivity, the book does not contain anything approaching an adequate treatment of inductance, capacity, and polarization effects. Nevertheless there is much in this text book that deserves high praise and that can be read with profit by both beginners and advanced students. We refer to the many applications of Onsager’s equation, the discussion of the solvent correction, the evaluation of the equivalent conductance a t zero concentration and finally the use of conductance methods in solving analytical problems in pure and technical chemical research. F. H. MACDOUGALL. Bearing MetaEs and Bearings. American Chemical Society Monograph Series, No. 53. By W. M. CORSE. 6 x 9 in.; 383 pp. New York: The Chemical Catalog Company, Inc., 1930. Price: cloth, $7.00. The author has surveyed the literature on bearing metals and bearings and has collected into one volume bibliographic references to the widely scattered publications in different languages and in many journals, the more important articles being abstracted. Part I (25 pages) presents a brief but interesting history of the development of bearing metals and bearings. This part serves to acquaint those not familiar with this field of work with some of the important subjects. Part I1 (106 pages) contains more than a thousand bibliographic references to articles on bearing metals, sliding-contact bearings, friction, and lubrication. The metals included are the white metals, the bronzes, and the graphite bearing metals. The bibliographic references are arranged under appropriate main and subheadings and cover the literature through 1928. Part I11 (108 pages) contains two hundred thirty-four abstracts of selected papers. These abstracts were specially prepared and give quite completely the important information in the original articles. Part IV contains sixteen tables showing the properties of bearing metals. This volume is a valuable contribution to workers and students in this field. I n looking up the published information on this whole field or on any special phase of it, much time can be saved by making use of the material which Come has collected and put into convenient and usable form. The author index contains about seven hundred names, and the subject index provides an easy means of finding the information on some two hundred subjects. OSCARE. HARDER. AND P. HARTECK.295 pages; Crundlagen der Photochemie. By K. F. BONHOEFFER 73 figures; 30 tables. Dresden and Leipzig: Theodore Steinkopff, 1933. Price: bound, 25 R.M.; unbound, 24 R.M. I n the three or four decades during which the study of chemical kinetics has been intensively pursued, it has become increasingly evident that there is no golden road to knowledge along which progress takes an easy course. This is equally or more true of photochemical kinetics. The technique is difficult; the theory, involving several domains of physics and chemistry, is complicated and incomplete. The Einstein law of photochemical equivalence and its experimental verification marked a milestone of substantial achievement; the application of the principles of modern spectroscopy to photochemical phenomena ushers in the newest phases of photochemistry. It is these principles and their detailed application to various photochemical
