three, with considerable improvement in the coherence of presentation of this very fundamental subject. Many of the major developments in the period between the appearance of the two editions have been concerned with a number of hreakthroughs achieved in the region of ultrahigh vacua (vacua less than mmj. Consequently, the revision of a number of the chapters has involved the addition of relevant new material. Also, the extensive list of references to original literature which was the mark of the first edition has been enlarged and brought up to date. Certain features which are a matter of detail have resulted in an improved tent. Thus, s complete list (with page reference) of symbols which are used in the many formulas appearing in the book is ver,y useful in expediting interpretation. Also, the increased size of print in many of the tables results in easier legibility. Although the text emphasizes the theory or principles involved in the production and measurement of high vacua, good bdance is achieved overall between theory and application. It maintains those characteristics of simplicity and clarity of presentation which combined with its thoroughness of scope has kept i t without peer as the fundamental reference in the field of high vacua. No person or labor* tory contemplating research in the region of high vacuum or ultrahigh vacuum should be without it. E. L. PACE Western Reserve Univemity Cleveland, Ohio
1961, as some 12 suthom have contributed to the work. The same general format employed previously has been retained, and the high standards have been maintained. Pascal's material is more recent than that published and planned for the current edition of Gmelin, and the treatment is more thorough. This part of the work, as well as that published in the other volumes to date, would indicate that it will be a reference work of greatest value in inorganic chemistry.
Near Zero: The Physics of Low Temperature
D. K . C . MaeDonald, National Research Council, Ottawa, Canada. Anchor Books (Doubleday & Co., Ine. j; Garden City, Piew York, 1961. 116 pp. Figures. 10.5 X I8 cm. 5.95.
Another in the PSSC series of supplemental readings which should appeal to chemists is this logpage pocket-sized hook telling the story of basic cryogenics. Written definitely for the layman or heROGERV. KRUMM ginner in science, it includes the history of the assault on absolute zero authenUniversity of Florida (Continued on page $608) Cainesville
Nouveau Trait; de Chimie Minbrale. Volume 15, Uranium et Transuraniens. Part 2, Combinairom de Isuranium
Edited by R. Caillat and J . Elston. Paul Pascal, general editor. Masson et Cie, Paris, 1961. I+ 639 pp. Figs. and tables. 17 X 26 cm. 110 N F broche, 122 NF, eartonne toile. The second part of Volume 15 of Pascal's new treatise deals with the derivatives and compounds of uranium. The first part was devoted to theelement primarily, although certain ionic aspects, such as valence states. oxidation-reduction. h>--
complexes and the organic derivatives. Thermodynamic aspects of interest in the separation of isotopes and physical properties of uranium compounds are also included, as well as the use of these compounds as nuclear fuels. While the third part will be devoted to the transuranium elements, this part has given some space to biological effects, toxicity, dangers, and protective measures to be considered in the handling of thorium, uranium, and transuranium elements. While the index might have been more thorough, the arrangement of chapters is felt to be effective, particularly the use of separate chapters on hydrogen, each of the halogens, and oxygen before groups of elements are considered together. The bibliographic searching ranges from 1957 to Volume 39, Number 8, August 1962
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