that, as a textbook, it will find widespread use and it is not likely that it was intended as such. However. the third edition has been brought up t o date with references to work which was published as late as the first months of 1932. As a result this edition may be expected t o occupy the same high place in the esteem of those chemists interested in the fields of colloid chemistry as did the previous editions. L. H. R ~ Y E R S O N U~msnsrrzos MINNBSOT* MINNEAPOLIS. MINN.
APPLIED X-RAYS. George L. Clark, Professor of Chemistry, University of Illinois. Second edition. McGraw-Hill Book Co., Inc., New York City, 1932. xiv 470 pp. 239 Figs. 15 X 23 cm. $5.00.
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The first edition of this book was intended by its author as a missionary, telling of the uses to which X-rays could be put. I t fulfilled that purpose admirably. Now that the pioneer missionary work has been so successfully done, the author is justified in feeling that the need a t present is for an elementary textbook on the subject. The second edition of "Applied X-Rays" is therefore really a new book, not merely a revision. I t is divided into two sections. The first, consisting of 170 pages, deals with the physics of X-rays, X-ray tubes and circuits, radiography, and the more physical applications of X-rays in chemistry and biology. The second section, consisting of 291 pages, deals with the use of X-rays in crystal analysis. The first part of this section reviews briefly the necessary basic knowledge of crystallography, and the diffraction of X-rays by crystals. This is followed by an outline of the experimental methods of crystal analysis and the interpretation of the diffraction data. The rest of the second section of the book is devoted t o a senes of r&um& of the results of crystal analysis. These results are classified as follows: crystal structure data for elements and inorganic compounds, generalizations in inorganic chemistry, structure of alloys, structure of organic compounds. grain size, orientation, industrial metallurgical problems. liquids and colloids, and polymerized organic materials. The result is a book well adapted to college seniors who have had a good basic training in physics and chemistry, and in physical chemistry and chemical physics. It could he used successfully in classes composed of seniors in the standard college curricula in physics, physical chemistry and chemical physics. or metallurgy. It is not intended to be of graduate student grade, but graduate students ought t o buy i t and use i t for private introductory reading in preparation for a graduate course in nvstal structure and its a~olications. . All teachers of chcmistry and metallurgy will find it a ralual>lc addition to their privntc libruries. I t ir sale to say thnt thcwe teachers who mud this book will i h o r the cfiecta in their lectures to their students. W x E ~ m nP. DAVEY TABPENNSYLVANIA STATE COLLB~&
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