W. ESPE and M. KNOLL, Werkstoffkunde der Hochvakuumtechnik, 1936, J. Springer, Berlin, R. M. 48.

V. ESPE and M. KNOLL, Technology of Vacuum Materials. 383 pp., 119 tables and 405 figs.

In high-vacuum technology, which has penetrated into every corner of the methodology of physical research and serves as the basis for the electrovacuum industry, one has to use, in the construction of various vacuum and gas-discharge devices, a whole series of different materials. The frequent and, in general, highly responsible use of these materials for one purpose or another in this case requires quite special criteria, such as, for example, good degassing properties, easy accessibility for machining, poor sputterability, certain electrical, emission, and mechanical properties at high temperatures, etc. All these special requirements have in the past led, finally, to the use of already existing materials and to the creation of a whole series of new ones. A very large and interesting body of material has undoubtedly accumulated in this connection in the laboratories and factories of the electrovacuum industry and in individual institutes carrying out research and semi-production work on a large scale; but, unfortunately, not all these data have become the property of all those working in this field. In this respect, the many small institutes, university laboratories, etc., were in a particularly unfavorable position, where vacuum technology, though widely employed, could not, for a number of reasons, conduct work toward improving this technology and the technology of the materials used; they were therefore forced to work in a handicraft fashion, to confine themselves to the rather narrow limits of a definite, sometimes perhaps somewhat obsolete, technology and methods of manufacturing and evacuating various instruments. A way out of this situation might lie in familiarity with, and knowledge of, a sufficiently complete and modern monograph on the technology of vacuum materials, which is within the capacity, of course, primarily of sufficiently competent workers in electro-

vacuum industry. In the past, some small attempts had already been made in this direction—it is enough to mention, by way of example, Ivanov’s small lithographed booklet Technology of Vacuum Materials (Svetlana, 1934), Simon’s article in Handbuch der Experimentalphysik XIII 2, and a few scattered references, chiefly in various books on vacuum engineering—but all this, of course, did not resolve the question. Therefore the appearance of such a serious manual on this subject as the book under review by Espe and Knoll is to be welcomed. The authors have been able to assemble in this book fairly extensive and varied material, of which some idea may be gained from the list of chapters of this book:

I — Introduction, II — Preliminary metallographic remarks, III — Refractory metals and alloys, IV — Platinum metals and alloys, V — Base metals, VI — Alloys of base metals, VII — Mercury, VIII — Alkali and alkaline-earth metals, IX — Electrographite, X — Special methods for processing vacuum metals, XI — Glasses, XII — Quartz glass and quartz materials, XIII — Ceramic materials, XIV — Luminous compositions, XV — Mica, XVI — Asbestos, XVII — Rubber, XVIII — Fats, oils, and sealing greases, XIX — Greases for bases, XX — Gases and vapors, XXI — Thermionic cathodes, XXII — Photoelectric cathodes, XXIII — Cold cathodes, XXIV — Getters, XXV — Vacuum-tight connections.

The book describes in great detail the various metals and alloys used in the technology of electro-vacuum devices, and at the same time gives detailed data characterizing their properties. Less detailed, though on the whole sufficiently so, are the descriptions of the properties of glass—this chapter, as a rule, is of less interest to the Soviet reader, since the data given in it refer to foreign glasses. The book then describes materials that are usually considered secondary, although at times they play by no means the last role, such as quartz, ceramics, mica, etc. The sections devoted to the manufacture of lamp fittings, various thermionic cathodes, the use of getters, and the like are interestingly presented in the book. In them we find some data on a whole series of new and as yet little-known materials, for example, on niobium, sintered-paste cathodes, various kinds of alloys, etc. The book is excellently produced, richly illustrated, and supplied with a whole series of explanatory tables, drawings, and photographs, which makes it very attractive. As examples one may point to the scheme for purifying inert gases, tables characterizing methods of applying and activating oxide and barium cathodes, drawings of the form of contacts in electric welding and methods of mechanically fastening electrodes, etc. As a result of all this, the book becomes very useful for workers dealing with vacuum technology, and interesting reading for them. Among the shortcomings of this book, apart from some individual passages (for example, the diagram shown in Fig. 271 illustrating the principle of operation of economical cathodes seems poorly substantiated, etc.), one may perhaps include the following: the authors present here a large quantity of diverse data, and therefore they should have helped the inexperienced reader to sort them out in the sense of indicating to him the most convenient and verified materials and methods and setting them forth in greater detail, even if partly at the expense of secondary ones, which the book undoubtedly contains. Then, despite the considerable size of the book, it would nevertheless have been useful to include some more detailed data on the field of vacuum technology, and especially on pumping and degassing techniques, the most characteristic lamp designs, etc.; from all this the book would undoubtedly have benefited still more. In conclusion, one should wish for the translation of this book into Russian, with appropriate revision, and first of all in the direction of including in it data from the practice of our Soviet institutes and the electro-vacuum industry.

N. L. Morgulis, Kiev.