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is of considerable economic interest; it is further enriched by a topographical survey, t h e earths found in various parts of the world being given under the place names. T h e sources of monazite are particularly well described. Out-of-the-way sources, such a s plants, animals, and coal ash, are not forgotten. Altogether i t may be said t h a t if t h e remaining sections of the volume on the rare earths are as good as this one, chemists will have reason t o be grateful t o the patient, careful, and accurate work p u t in by the editor and his collaborators. J. R. P A R T I N G T O N . Gmelins Handbuch der anorganischen Chemze. 8 Auflage. Herausgegeben von der Deutschen Chemischen Gesellschaft. System-Summer 25: Caesium mit einem ix 105-268. Anhang uber Ekacaesium. Lieferung 2. 26 x 18 cm.; pp. xx Berlin: Verlag Chemie, 1938. Price: 21.75 RM. This section deals with the compounds of cesium and completes the volume on this element, the first part having dealt with the element. Compounds with hydrogen, oxygen, nitrogen, halogens, sulfur, selenium, tellurium, boron, carbon, silicon, phosphorus, arsenic, antimony, bismuth, and double salts with other alkali metals, and oxy compounds are fully dealt with. The order is t h a t adopted in all volumes of Gmelin’s Handbuch and goes back t o the old issue, the periodic order not being followed. I t goes without saying t h a t all the information is complete, up-to-date, and critical. T h e literature on ekacesium is fully and critically reviewed and t h e conclusion is reached t h a t “in the present stage of investigation, ekacesium either does not exist a t all OP exists only in extremely minute amounts.” J. R. P A R T I X G T O N .
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Gmelins Handbuch der anorganischen Chemie. 8 Buflage. Herausgegeben von der Deutschen Chemischen Gesellschaft. System-Kummer 27 : Magnesium. Teil B. Lieferung 3. 26 x 18 cm.; pp. xiv 331-422. Berlin: Verlag Chemie, 1938. Price: 12 RM. This section includes cyanogen compounds, the formate, acetate, oxalate, tartrate, and compounds with silicon, phosphorus, arsenic, antimony, and bismuth. T h e organic acids are those chosen for inclusion in all parts of the Handbuch and represent those which form compounds of interest in inorganic chemistry. T h e information is very complete and critical on physical and physicochemical properties; numerical data, a s well as the preparative and chemical properties and reactions, are given. T h e information is based on t h e latest literature, this being clear in the section on t h e phosphates, for example, and in some cases patent literature is reviewed; it is stated, for example, t h a t magnesia is used in sugar refining. The section on silicates is very complete and well documented and is of considerable interest from the mineralogical side. The section is an excellent example of the high standard of the whole work.
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PARTINGTOX.
The Properties of Glass. By GEORGEW. ~ I O R E Y 561 . pp. Kew York: Reinhold Publishing Corporation, 1938. Price: $12.50. This volume, which is an important contribution t o the literature on glass, comes from the pen of one whose personal researches rank him as a leader in physicochemical development in t h e field of glass technology. I t is natural, therefore, t h a t he should stress the physical properties and testing of glass. The introductory chapter on history and definition is unique, in t h a t i t includes archeological material a s well as glass production. Chapter 11, on devitrification, is a masterly presentation from the standpoint of the phase law, with which the
N E W BOOKS author has been greatly occupied. I n chapter 111, on composition, the section on volatile substances and their adsorption is timely, together with the permeability of glass t o gases. Chapter IV, on chemical durability, discusses composition and testing, indicating discrepancies in the various methods employed for a given determination. Chapter V deals with the measurement of viscosity and theoretical considerations not only for glasses, but also for slags and minerals. Chapter VI, on annealing, discusses the detection and measurement of strain, the development of strains in glass, and methods for their removal. The annealing of common types and special glasses is included. In chapter VII, on surface tension, units are listed with experimental results of their application. Chapter VIII, on the heat capacity of glass, discusses single- and multi-component systems. Chapter I X covers thermal conductivity, providing mathematical formulae and data for individual glass-making oxides. Chapter X, on density, gives the individual values commonly employed in additive calculations and applies these t o uni- and multi-component systems. Density is discussed not only a t ordinary temperatures, but also for higher temperatures. In chapter X I thermal expansion, methods of measurement, and the effect of heat are treated. Chapter X I 1 deals with elastic properties. Compressibility, and the effects of temperature, pressure, and strain on elastic constants, are followed by a discussion of the elastic after-effect. In chapter X I I I , on the strength of glass, units and various component systems are given with a comparison of the strength of fibers and tubes. The effect of strain on strength, of duration of load during tests, and finally that of temperature on strength is indicated. In chapter X I V thermal endurance and optical differences with temperature changes are illustrated. I n chapter XV, on hardness, the uncertainty and variation of values is indicated, and i t is clear t h a t this property cannot yet be satisfactorily determined by any standard method. Optical properties are discussed in chapter XVI. After defining the units, t h e author lists experimental methods for determination of refractive index and dispersion. Valuable data are provided for a great variety of glasses. Finally, t h e effect of pressure on optical properties is covered, with units and experimental data given, and a short section covers transmission values for colored glasses. This is one of many valuable chapters in the book. In chapter XVII the electrical conductivity of glass, which was covered more extensively i n the “Electrical Properties of Glass” with J. T. Littleton in an earlier publication, is given generous treatment. Chapter XVIII, on dielectric properties, treats the effects of frequency, temperature, chemical composition, surrounding media, and applied voltages, and discusses the nature of dielectric failure. Variations with thickness are also covered. Chapter XIX, on magnetic properties, deals with the Faraday and Kerr effects. The last chapter, chapter XX, on the constitution of glass, stresses the importance of x-ray analysis, variations of this with temperature, and changes on annealing. The difference in the appearance of pure crystals and glasses is illustrated and emphasized. Not all technologists will agree with the author concerning methods t o which he has given preference. The applicability of a particular method for a special case may vary with the type of glass. Very frequent reference t o the author’s publications clearly indicates the extent of his own contributions. I n the index errors occur occasionally, but there is an abundance of cross reference information. A supplementary index on the properties of glasses in various systems is an aid rarely encountered in publications. Dr. Morey’s volume is a precious addition t o the literature on glass. ALEXANDER SILVERMAN.
