evidence and its clear delineation of the particular flaws and limitations thereof the student is spared the ez cathedra approach 80 often encountered, realizes more than is usually possible the tme validity of our information and concepts, and may even be stimulated to independent thought. I t is bard to read certain portions of Pmfessor Wheland's book without trying to elaborate experimental solutions to some of the problems he indicates as currently unanswered. Hisis unquestionably a more penetrating and hence more stimulatine book thzn most of its tvne. Interest " .~ ~ ~~

is heiehtened bv freauent historical mat,erial. and nonulnr mic " ~. ~~ - ~ ~ ~ - ~~~~~~~~~ , r~r-~..- -~- .~ conceptions of historical priority are clarified in several instances.

Possible criticisms of the book are for the most part trivial. The usual lucidity of the writing sometimes approaches verbosity, and inconsequential meterid is occasionally developed in too painstaking detail. Considerable space is wasted in printing and designating with Roman numerals the fomulas for simple oraanic com~ounds when the name alone would suffice. In some se&ons of the hook the number of illustrative examnles is P X P ~ ~~ ~ . ~ ~~ ~~~

siw, with nothing new a d d d i y the repetition. The owadonal use of It.trer~ orher than X to dr4wstc nlkyl groups might prime

confusing, nnd the use of simple hexngms, rlther than 1it.kule structures, to designate aromatic rings seems unfortunate since i t requires the use of more cumbersome structural formulas for cycloalhne derivatives. Remaining criticism is more from the viewpoint of omission. The qualitative molecular orbital treab ment might profitably have been included in the chapter on resonance which, incidentally, gives a somewhat over-optimistic impression of the applicability of quantum mechanics to organic chemistry. More recent examples of steric effects and s. discus- sion of the steric inhibition of resonance might have added to the treatment of steric phenomena. The question of orientation in aromatic substitutions is largely ignored, as are, explicity a t least, the topics of structure and oolor, ultraviolet and mfrared spec- troscopy, and detailed treatments of most modem physical meth- ods of structural investigation.

Organic chemistry is currently so broad that perhaps no single point of departure is adequate for a completely satisfactory treittr m a t . Thus, omissions and differences of opinion regarding desirable emphasis are probably inevitable in any text. It is therefore to the author's credit that he has produced so logical and adequate a book from the classioal viewpoint of structure. The excellence of Pmfessor Wheland's book is certain to insure its widespread use ns a single-volume advanced text.bmk of or- ganic chemistry.

WILLIAM A. BONNER

0 PHENOMENA, ATOMS, AND MOLECULES

Inring Longmuir, General Eleotric Corparation, New York. Philosophical Library, Inc., New York, 1948. xi + 436:pp. Dlustrated. IS X 23 cm. $10.

THIS book is a collection of twenty papers which were published by Langmuir since 1909. They have been assembled, in eighteen chapters, to f o m this very interesting volume. These chapters are:

I. Science, Common Sense, and Decency; 11. Discussion of Science Legislation; 111. World Control of Atomic Energy; IV. Surface Chemistry; V. The Constitution of Liquids; VI. The Distribution and Orientation of Molecules; VII. Atomic Hydrogen and an Aid to Industrial Research; VIII. Flames of Atomic Hydrogen; IX. The Dissociation of Hydm gen into Atoms; X. Forces near the Surfaces of Molecules; XI. Isomorphism, Isosterism, and Covaleuce; XII. The Effects of Molecular DDissymmetry on Properties of Matter; XIII. Metastable Atoms and Electrons Produced by Resonance

JOURNAL OF CHEMICAL EDUCATION

Radiation, in Neon; XIV. The Condensation and Evapo- ration of Gas Molecules; XV. The Evaporation, Condensation, and Reflection of Molecules and the Mechanism of Adsorption; XVI. The Evaporation of Atoms, Ions, and Electrons from Caesium Films on Tungsten; XVII. The Mobility of Caesium Atoms Adsorbed on Tungsten; and XVIII. Types of Valence.

A s may be seen from the list of chapter headings, some ma- terial is included from nearly every one of the author's various lines of researoh. This book is valuable for the reason, then, that many of these classic papers are collected under the same cover, even though some of them are very well-known, and others con- tain disewsions which are now obsolete.

In spite of the rather flamboyant title, this book should he a valuable (if rather expensive) addition to the library of anyone interested in a representative collection of papers by a leading scientific figure of our day.

0 VACUUM EQUIPMENT AND TECHNIQUES

Edited by A. Guthrie, Radiation Laboratory, University of Cali- fornia, Berkeley, California, and R. K. Wakeding. McGraw- Hill Book Co., Inc., New York, 1949. mii + 264 pp. 102 figs. 25 tables. 16 X 24 om. $2.50.

Tms book is Volume I, Division I, of the Nationd Nuclear Engineering Series of the Manhattan Project Technical Section. It makes available the rather extensive experience gathered at the University of California Radiation Laboratory in the course of developing high vacuum equipment for use in the electro-mag- netic separation plants. The material presented by several au- thors is arranged in an orderly fashion and will be of practical value to laboratory workers who are making use of this increas- ing field of vacuum technology. Since a great deal of the de- scriptive practical material pertains to the larger scale vacuum systems, persons interested in industrial vacuum engineering will find the book of great use also.

I n the initial chapter by R. Loevinger, the basic theory of vacuum practice is presented and the quantities which cbmacter- ize vacuum systems sre dehed snd related to one another. The elementary parts of a vscuum system are described and dis- owed by W. E. Bush in Chapter 2. Chapter 3, by K. M. Simpson, gives in detail the methods for measuring low pressures while materials and equipment for construction of vacuum s p tems are discussed by W. E. Bush in Chapter V. The final chap ter by R. Loevinger and A. Guthrie describes the methods for trouble-shooting and maintaining vacuum systems. Appendices contain a list of symbols, a summary of formulas useful in design of vacuum systems, physical properties of gases and vapors, a l is t ing of mechanical m d diffusion pump oils together with their prop erties, data on cold traps and drying agents, and miscel- laneous vacuum materials and same solids and liquids encoun- tered in vacuum practice.

The selcctian of materials, its arrangement, and the many figures and tables will make this book very useful as a reference volume. Because of the background for the book, metal vacuum systems are emphasieed, as me fasbpumping systems. While such systems comprise the largest bulk of the modern vscuum work, laboratory workers using small scale glass equipment may not find much material that is of specific value. The book does not have much to say about the various applications of vacuum practice but the many references, if used, will accomplish this end.

JOHN P. HOWE GENWC ELBCIWC CO.

Kaoms A~olarc Powxa L~sosmonr. Scanrwr*o~. New Yonr