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NEW BOOKS
The present section deals entirely with the technical preparation of potassium salts. After historical and economic sections (the latter with useful tabulated statistics of production from 1881 to 1936,from which i t appears that Germany and France are now the main producers), the text deals with methods of extraction from the raw materials and the preparation of each of t h e technically important potassium salts. There are long sections on the treatment of carnallite and kainite, including the working up of the magnesium salts. The text is descriptive and there are no phase rule diagrams. Felspar, leucite, glauconite, cement kiln and blast furnace dusts, sea water and sea weeds are given as sources, and there is a brief section on organic sources, but wood ash and suint do not seem t o be included. The present section, i t will be seen, is of considerable technical interest. The main emphasis is on the Stassfurt sources, for which more information is available than is the case for some of the other technical sources. J. R. PARTINGTON. Reports on Progress i n Physics. Volume V. Published by the Physical Society (London). 26 x 18 cm.; iv 445 pp. Cambridge: The University Press, 1939. Price: 20s. The present volume of annual reports deals with the same general range of subjects as previous volumes, but the sections on electricity are much shorter and room is found for special topics such as adsorption in solutions, recent theories of the liquid state, plastics, instrumental aids to defective hearing, electric wave filters, cosmic rays, and the teaching of physics in schools. The standard is high, and the aim set out in the preface that the volumes shall be intelligible and interesting to non-specialists and a t the same time informative and suggestive to workers in special fields, is perhaps as nearly realized as i,s possible. Physical chemists will find much t o interest them in the present volume. J. R. PARTINGTON.
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The Elements of Physical Chemistry. By F. W.GODDARD A K D E. .J. F. JAMES.viii 251 pp.; 67 figures. London: Longmans, Green and Company. Price: $1.80. This little book is designed for the study of physical chemistry by students in England who are preparing for Higher Certificate, First Medical, and University Entrance Schblarship Examinations. At the conclusion of each chapter questions and problems are inserted of the kind t h a t might be met in the above-mentioned examinations. There are two hundred and fifty such questions and the answers are given in an appendix. The ten chapters cover the usual topics i n a beginning book in physical chemistry: atomic structure; gaseous and liquid states; solutions; osmotic pressure and colligative properties; mass action; thermochemistry; electrolytes; catalysis; and colloids. The treatment is concise. Students in this country should find the extended list of problems with answers valuable in their own study of physical chemistry. GEO. GLOCKLER. Electron Optics. By the Research Staff of Electric and Musical Industries Limited. Compiled and written by Otto Klemperer. 8+ x 5+ in.; 84 figures; x 107 pp. Xew York: The Macmillan Company. Price: $1.75. This volume is the third addition t o the new series of the Cambridge PhysicaE Tracts and gives an excellent account of a very modern and important topic. The use of electron beams functioning as light rays and their diffraction in electrostatic and magnetic fields opens up an important field of physics. The resolutions already
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