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NEW BOOKS
predissociations, alternating intensities and nuclear spins, and electron impact processes. Most of them are based, as Dr. Sponer very generously acknowledges, on the corresponding tables in the reviewer’s Report (Physical Society, 1932), supplemented by more recent data and by columns giving electron configurations and dissociation products. For polyatomic molecules the tables, which are entirely new, cover infra-red and Raman spectra (with diagrams showing modes of vibration), electronic bands, and electron impact processes. Data published while the rest of the volume was in the press in 1934 and early 1935 are included in two supplementary tables. A brief explanation and a list of references accompany each group of tables, and the work is well indexed. Remarkably few omissions and numerical errors have been detected. The compilation, which represents a vast amount of careful work, will be invaluable to spectroscopists and chemists. W. JEVONS.
Gnaelins Handbuch der anorganischen Chemie. 8 Auflage. Herausgegeben von der Deutschen Chemischen Gesellschaft. System Nummer 53: Molybdan. 25.5 x 17.5 cm.: xi 393 pp. Verlag Chemie, 1935. Price: 64 marks. The present volume deals with the ores of molybdenum, the extraction, refining, and physical and chemical properties of the metal and i t s alloys, and with the chemistry of the compounds of molybdenum, including the heteropolyacids. The treatment is very detailed and physicochemical aspects are well represented. The book contains a wealth of accurate and well-arranged information, and the literature is covered till the end of 1934. J. R. PARTINGTON.
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Kristallplastizitat. By E. SCHMID and W. BOAS. 22 x 15 cm.; x 373 pp. Berlin: Julius Springer, 1935. Price: 32 marks (paper covers), or 33.80 marks (bound). The study of crystal plasticity has made remarkable progress in recent years; this has been achieved by a number of workers largely independent of each other, and not infrequently approaching the problem with different aims. For example, the plastic nature of the crystalline state is of great importance to the engineer in his search for special alloys; the chemist and physicist, however, are more concerned to extract what they can to shed light upon the nature of the forces acting in the lattice. The authors of the present book have in fact provided an encyclopaedia of all that is at present known about these matters, with special reference t o metals. The volume falls into three parts,-general, special experimental results, and the significance of the effects shown by single crystals. An idea of the scope embraced by the writers can be gathered from the list of references collected a t the end, which number over seven hundred entries. The discussion of hardness in ionic crystals is exceptionally clear. Two points are stressed (which even to-day need underlining), firstly that hardness is not a definite quantity, but only has a meaning when expressed in terms of a particular method of determination, and secondly, that the time is not yet when we can link such observations with crystal strength, and consequently, no doubt, with lattice properties. Scratch-hardness curves for rock salt and fluorite on the (100) and (111) faces are delightful illustrations of the anisotropy of a surface. The same is true of the pendulum method for rock salt on (OOl), yielding maximum values of about 0.5 with an interveningminimum as low as about 0.2. The price of the book is very high, but for those wishing t o have all the information there is to be had about plasticity in crystals, this book should be invaluable. As in the case of other Springer publications, the format is excellent. F. I. G. RAWLINS.
