BOOK REVIEWS chemistry, and in most cases new data is presented. It ir a book which should be extremely useful to any teacher anxious to enliven his lectures on aromatic character with examples of current research. The hook properly begins with a brief but excellent biography of A u p s t Kekul6 written by Peter Verkade. This is followed by a thought provoking srticle by Linus Pauling on aromatic bonds. His suggestion that the modern sigma-pi description of unsaturated bonds is less satisfactory than che older bent-bond ideas will attract the rebel in college students, and should provide excellent material
for organic seminars. Chapters on The Ground State of Some r-Electron Systems by Lonquet-Higgins, Aromatic Character by D. P. Craig, Stabilization Energies and Strain Energies by Heats of Hydrogenation by R. B. Turner, and Molecular Geometry and Steric Deformation by C. A. Coulson, should aid the student in putting the Hiickel rule in its proper perspective, and provide some interesting areas of uncertainty open to investigation. Doering provides a nice summary of the non-benzenoid cyclic 6r-electron systems of cyclopentadienide and eycloheptatrienylium ionsin his chapter on Tropylium and Related Molecules. Modern problems of aromatic substitution are discussed from several angles. J. F.
Bunnett relates Nucleophilie Substitution a t Unsaturated Centers to aromatic nucleophilio substitution, while R. Huisgen summarizes recent work on the benayne intermediate in Recent Developments in the Elimination Mechanism of Nucleophilic Aromatic Substitution. Nitration by E. D. Hughes and Some Recent Studies of Reactivity and Orientation in Aromatic Halogen Substitution by Peter de'la Mare cover the area, of electrophilic substitution. New work on Hydrolysis of Diaryliodonium Sslts is reported by J. D. Roberts and co-workers, and by 0.A. Reutow (in German) in Polare Faktoren in der Zerseteungsreaction unsymmetrisoher Jodoniumsalze. Aromatic Rearrangement is discussed by M. J. S. Dewar, and radical reactions are considered in chapters by D. H. Hey (Homolytio Substitution Reactions in the Naphthalene Series) and M. Sswarc and J. H. Binks (The Behavior of Radicals in Addition and Abstraction Reactions). The remaining chapters deal with special areas of current interest not so closely related to aromatic chemistry. These are Some Recent Progress in Conformational Analysis by D. H. Barton, Frrtgmentation in Salvoly~is Reaotions by C. A. Grob, Nucleophilic Octahedral Substitution by C . K. Ingold, and Quasiheterolytic Reactions in the Gas Phase by Alan Maccoll. I found myself making frequent changes and improvements in my lecture nates on aromatic chemistry as I read these srimulating chapters. The book is a valuable monograph which will likely have to he kept on the reserve shelf. E. CAMPAIGNE Indiana University Bloornzngton The Structure of Electrolytic Solutions
Edited by Walter J . Hamer, National Bureau of Standards, Washington, D. C. John Wiley and Sons, Inc., New 441 pp. Figs. and York, 1959 xii tables. 16 X 23.5 cm. $18.50.
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This book is a collection of the papers presented at an International Symposium on Eleotrolytes sponsored by the Theoretical Division of the Electrochemical Society and the National Science Foundation and held at Washington, D. C., during May, 10x7
This reviewer attended the symposium and can attest to its excellence both as to the quality of the papers and the contributors and to the organization of the meeting in general. The meeting was truly international in character and the list of contributors eontsins the names of many of the outstanding scientists in the electmlytic field today. Perhaps the most outstanding feature of the book is the scoDe of the material Dresented. The topics covered range f&rn dilute solutions, through concentrated solutions and fused salts to ionic crystals. Besides aqueous solutions, various data. for non-aqueous and solvent mixtures are discussed. As the title suggests, the problems of structure are emphasized along with mechanism. In many cases (Continued a page Ai76)
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Journol o f Chemical Education
BOOK REVIEWS improved models are proposed to explain various phenomena. The two papers on the Soret effect constitute an important contribution since that field has been neglected in the past. The review paper on the state of the proton in aqueous solution covers the topic quite adequately and contains references to many of the more recent papers in this field. The other topics covered include activity coefficients and viscosity effects in concentrated aqueous solutions and Raman spertral investigation of ionic equilibrium in such solutions; proton transfer in aqueous, methanol-water, and hydrogen peroxide systems; ionization constants for various systems obtained from emf, conductance, high field condnctrtnce, and spectrophatometric measurements; pH in non-aqueous solvents; electrolytic properties of the rare earths; electrophoresis and conductivity in ~olutions containing polyelectrolytes; diffusion in binary and ternary systems, ionic vibration potentials, anion exchange of metal complexes and complex ions in molten salts; thermodynamic properties of aquo-ions and ion pairs with an application of cryst,al field theory; melting mechanisms of ionic crystals It is regrettable that a few papPrs a n the program of the symposium, particularly those of J. E. Mayer, J. G. Iiirl
