Recent Books Principles of Metdography. ROBERT S. WILLIAMS, S.B., Ph.D., and VICTOR0. HOMERBERG, S.B., P.D., Sc.D., Massachusetts Institute of Technology. Second edition. McGraw-Hill Book Co., 259 pp. New York City, 1928. ix 254 figures. 14 X 20.5 cm. S . 0 0 .
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The six chapters in this tent are entitled: The Simple Alloy Diagram: Laboratory Methods in Metallagraphy; The Alloy Diagram and Its Meaning; The NonFerrous AUoys of Technical Importance; Iron and Steel; The Macroscopic Enamination of Steel. The authors' pwpose as stated in the preface is "to give t o the. general reader the fundamentals of metallography and t o serve as an introductory text for those who are t o specialize in the field of allays." Two very commendable features impress the reader a t once; the numerous and exceedingly well-done microphotographs and the lucid and interesting style of writing. The more strictly chemical aspects of the suhject are covered in the first and third chapters which give a fairly complete account of the various types of alloy diagrams. The Phase Rule is taken for granted and used but sparingly. Possibly the student would get a better idea of the processes involved in forming a n alloy if more cooling curves were included and the meaning of their various parts discussed. For the student of chemistry who desires t o get a more practical idea of metallography than can ordinarily be obtained from chemistry courses, the chapters on Laboratory Methods and the Macroscopic Examination of Steel can he especially recommended. The appendices of Outline of a Laboratory Course, References, Industrial Alloys, Etching Solutions. Tem~eratureConversion Table and Melting Point and Atomic Weight Table
all add t o the book's usefulness. Unfortunately, no author index is included, though numerous references are included as footnotes. Findlay's name is misspelled "Findley" on page 18. The mechanical construction is the usual high quality of the McGraw-Hill publications. This tent can be most heartily recommended t o all chemists who desire to obtain a brief insight into the subject of metallography and its methods. W. M. HOSKINS Radio-Elements as Indicators and Other Selected Topics in Inorganic Chemistry. F R I PANETH. ~ Professor in the University of Berlin. The George Fisher Baker Non-Resident Lectureship a t Cornell University, 1926-27. McGrawHill Book Company, Inc., New York, 1928. 164 pp. 27 illus. 15 X 22.5 cm. $2.50. This volume, dedicated to Professor Arthur Wesley Browne, contains the material of lectures delivered in English, then written in German, and later translated by Doctor Martha Doan. Three main topics are discussed: The Use of the RadiaElement as Indicators, The Group of Volatile Hydrides, The Natural System of the Chemical Elements. "The general principles underlying the use of radio-elements as indicators is based on the existence of an isotopic relation hetween certain of the well-known inactive elements and the radio-elements. Since isotopes show identical chemical properties it is possible to substitute a radiaelement for its inactive isotope and to acquire information concerning the element in extremely dilute solutions." Thus bismuth and thorium C are identical chemically. The processes of diffusion, solution, and volatilization are studied with mixtures of the active and inactive
