449 can scarcely be regarded as a textbook for the chemical microscopist. For the student, however, who wishes to acquire a working knowledge of general microscopy, or for the person who desires a reliable guide to the technic of one of the most fascinating of all hobbies, i t is to be recommended without reservation. The directions for photomicrography are particularly good. One feature of the book will appeal especially to the hobbyist: although the reader is introduced to commercial professional equipment and accessories, numerous suggestions for the hameconstruction of inexpensive yet practical substitutes are offered. Orro REINMUTH ELEMENT~RY PRACTICAL CHEMISTRY.Arthur I. Voiogcl, DSc. (London), D.I.C., F.I.C.. Head of Chemistry Department, Woolwich Polytechnic. Blackie&Son,Limited, London, 1936. 220 pp. 73 figs. 12.5 X 18.5 cm. 3s. I n the preface to the 163 experiments of this laboratory manual the author describes his work and viewpoint as follows: "A fairly comprehensive series of experiments in somewhat greater detail than is usual in laboratory manuals of this kind is given: a brief description of the underlying theory is included in order t o bring home t o the student the real purpose of the experiment. It is the author's view that a sound foundation of the principles of practical chemistry (and simultaneously a better appreciation of his theoretical work) is best provided by giving the student full working details of the correct methods of carrying out experiments, and the so-called research method is best postponed to a later stage." The author's description is accurate and he is to be commended on the success with which he has met the specifications of his preface. Not only are the details of procedure carefully given but also in most cases the results are described, and balanced equations are provided. One is delighted to find many new and ingenious experiments among the old favorites.
ELEMENTARY PRINCIPLES IN PRYSICAL CHEMISTRY with Special Reference t o the State of Equilibrium in a Chemical Reaction and to the Rate of Attainment of the State of Equilibrium. T. J. Webb, Assistant Professor of Physical Chemistry in Princeton University. First edition. D. Appleton-Century Company, Inc., New York City, 1936. x 344 pp. 26figs. 67 tables. 15 X 22 cm. $4.00. According to the preface: "This textbwk has been written as an introduction to the subject of physical chemistry primarily for juniors and seniors in college. I t has been assumed that such students would have had preliminary training in the descriptive phases of chemistry, in general physics, and in the calculus . It has been the purpose of the author to introduce the principles and to make the derivations in a manner sufficiently general that they would not stand in need of constant revision as more advanced stages of thc subject are reached. As an inevitable result the treatment is t o some extent analytical and mathematical . ." That this is not "just another physical chemistry textbook" is evident from a mere listing of the chapters: "Introduction, The First Law of Thermodynamics, Chemical Equilibrium. The Second Law of ~hermodynamics,Equilibrium between Phases, The Thermodynamic Properties of Strong Electrolytes, The Rates of Chemical Reactions, and The Quantum Theory." Among the departures from the usual field of the "elementary" text are: rather detailed mathematical discussions of Maxwell's distribution law. Boltzmann's principle, mean free path, number of collisions, and the viscosity of gases. The heat capacity of gases is rather thoroughly discussed from the point of view of the separate contributions of translation, rotation, and vibration, and the quantization of the energy, particularly that of vibration. I n the treatment of the Debye-Hiickel theory, Poisson's equation is first developed in considerable detail. The mathematical details of the simpler theory are then given with great care. The chapter on the quantum theory (46 pp.) deals with the electron in its particle and in its wave aspects, with Schrijdinger's
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equation, with the energy states of a free particle, a particle in a box, the harmonic oscillator, and the rotating diatomic molecule. The discussion is closed with the correlation of Pauli's exclusion principle with the numbers of electrons in the various shells, and with their quantum numbers. Errors, typographical and otherwise, are remarkably infrequent for a first printing. The reviewer fears that the average undergraduate student of physical chemistry lacks the preparation and the ability to profit greatly by the use of this book, and that its use with such students would lead t o feelings of discouragement and despair. The book should, however, be of very great service in an "honors course" or in a course for graduate students who have already had a beginning course in physical chemistry. But even in these cases the teacher should be able and willing t o give the students material help in the more difficult places, and should frequently supplement the very general discussion in the text by additional specific and concrete examoles.
IN GENERAL C H E M I ~ ~ Y - Laboratory A Manual. S T ~ Urjrrs Y W . E. Bradt, Ph.D., Assistant Professor of Chemistry, State College of Washington. D. Appleton-Century Co., New York City, 1936. xvii 178 pp. 15 X 22 cm. $1.50.
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The author's purpose (stated in an accompanying "Guide for the Instructor") is t o subdivide chemical instruction into groups of topics, each presenting a definite task; to develop systematic reading habits; to create interest in chemistry, through references t o books or journals in popular style; t o foster efficient individual instruction. The experiments described are of a simple type, suited to high-school students or beginners in college work. They are in no sense unusual or original, but manipulative directions are carefully set forth, and numerous references t o current textbooks are given. Thirteen of the twenty "study units" may be classified as descriptive chemistry of the individual elements and compounds. and only six relate to simple theory, such as the approximate determination of atomic weights by the law of Duloug and Petit, combining proportions by weight, molecular weights, volumetric titrations, and the periodic law. Many teachers would wish more attention paid to such fundamental matters as chemical equilibrium, catalysis, the nature of acids and bases, oxidation and reduction, electrochemical principles, the choice and use of indicators. This b w k raises many interesting pedagogical questions, which different teachers will answer in different ways. Should the topics of descriptive chemistry be classified under individual elements or would i t be better t o present them as illustrations of general principles? Should laboratory work be intimately interwoven with a study of reference texts, or should it be made to develop something different in nature from that developed by the study of any text, namely, the capacity to obsme and to rearonfrom what i s observed? Should a laboratory manual include any questions that may be answered merely by looking up the answers in a textbook? Is there any danger that balancedchemical equations, introduced too early, may tend t o make chemical study a species of algebra, and interfere with training in capacity t o observe and to reason from what is observed? Should nut a laboratory manual hecome more difficult, and manipulative directions mare brief and concise, as the student makes progress through it? Is not laboratory work intended to give training in the application of the scientific method; if so, should not laboratory exercises present real problems, to be solved by observation and inference, rather than facts of descriptive chemistry t o be verified? Is the resolution of a science into disconnected "study units" c h i d y to be recommended because i t tends t o make the instructor's task an easier one or because i t helps the student t o see relationships that would otherwise be missed? If the latter is true, is there not danger that equally important relationships, which happen to crass the boundaries between arbitrarily chosen "study units," may be obscured? Should not many experiments, heretofore usually included in laboratory
