552 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS of germanium, tin, and lead are admirably covered for the period 1937-1964. Although an addition to the title "Including biological activity and commercial application" not present in Volume I implies an extension of the coverage of the subject there is the most meagre list of references in this area. In 155 pages devoted to germanium com- pounds there are only two biological references, both to toxicity. As previously, the information on applications is that gleaned from the patent literature. This is a book for synthetic chemists. The field of applications has been neglected by comparison and would seem to offer great scope for the future. j. M. BLAKEWAY. PRACTICAL EMULSIONS. Vol. 1. Materials and equipment. H. Bennett, J. L. Bishop and M. F. Wulfinghoff. Pp. vii q- 181 q- Ill. (1968). Chemical Publishing Co., New York. $12. Mr. Bennett's original text has now been brought up-to-date in a third edition and, as in the original, sets out to provide a comprehensive review of emulsion technology. This book will be of most use to a recent graduate becoming involved for the first time in emulsion technology and the references to the "laboratory neophyte" show the authors had this much in mind. The title "Practical" emulsions is perhaps slightly misleading since the main value of the book will be to provide a broad picture of the types of materials, equipment, processing and methods of testing which are used. The book is full of lists describing in brief, but concise terms, the scope available in each of these areas. However, should one wish to engage in practical emulsion tech- nology one would need to go further than this book, and one would question whether the references provided are perhaps as full as might be desirable for somebody seeking to gain practical experience in specific aspects. Whilst most of the references are reasonably recent, there is one on the emulsification of mineral oil dated 1909 and another from 1920 on optimum foaming with a number of compounds, and one does wonder if this is still very relevant in view of the speed of development in the chemical industry. The book concludes with an up-to-date list of emulsifying agents and their com- position which is satisfactorily comprehensive and a good Glossary of technical terms. For the new emulsion chemist this should be a very useful survey of the field however, English readers might find the price of f5 a little high for this purpose. C. PUGH. DISCUSSIONS OF THE FARADAY SOCIETY, No. 42 1966: COLLOID STABILITY IN AQUEOUS AND NON-AQUE- OUS MEDIA. Pp. 322 -+- Ill. (1967). The Faraday Society, London. oe5. Research into colloid stability is of fundamental importance to anybody inter- ested in cosmetics, and the current report of this 1966 discussion of the Faraday Society is, therefore, of potential interest to all the readers of this Journal. The papers tend to reflect the predictable balance between fundamental and applied research in

BOOK REVIEWS 553 that those from universities and research institutions outnumber those from industry by over 4 to 1. Of the 4:2 authors most have names that are household words amongst cosmetic chemists and so are the names of many of the :247 attending the discussion. Many industrial cosmetic chemists rely on practical methods which have stood the test of time for developing and proving the stability of their emulsions, rather than on theoretical arguments in their development. It therefore would be of considerable benefit to all such practical chemists to study this volume which brings up-to-date our knowledge of the theoretical developments, and of the recent experimentation into many of the theories of emulsion stability. The initial part of the volume deals with interface problems studied by work on the rupture of films, on the influence of the electrical double layer on stability, and the influence of boundary films on stability. This naturally leads into studies of stability in model systems of uniform particle size dispersion and to the influence of water at the boundary in both aqueous and non- aqueous dispersions, and finally, to the study of the influence of polymers at the inter- face. It is clear that an immense amount of clarification and support of the theoretical basis of emulsion chemistry has been achieved since the papers were published in 1940 for the first discussion on the electrical double layer which had to be cancelled by the outbreak of war in 1939. However, as with so many research discussions this very clarification has shown a number of areas where further investigation is needed to explain the anomalies which have emerged and to fill in the still evident gaps in our knowledge. This is a collection of papers which can well be recommended to all cosmetic chemists for study. C. PUGH ADVANCES IN ORGANIC CHEMISTRY: METHODS AND RESULTS. Vol. 5. Editors: R. A. Raphael, E. C. Taylor, H. Wynberg. Pp. vii + 337 + Ill. (1965). John Wiley & Sons, New York/London/Sydney. 105s. Contributions in previous volumes of this series have presented a critical appraisal of a synthetic method (nine), or of intermediates and reagents (six), or diagnostic techniques (four) or degradation (one) in addition one account described the novel chemistry of a specific natural product (muscarine). The fifth volume appears to have moved away somewhat from this ambit: while nearly two thirds of the book is allocated to a comprehensive review by M. Tichy (Prague) of the ir spectro- metric investigation of the stereochemistry of intramolecular hydrogen bonds, the remainder comprises a discussion by A. J. Parker (Western Australia) of the use of aprotic solvents in organic chemistry, and a characteristically concise but remarkably readable survey of polycyclic diterpenoids contributed by the former Barton collabor- ators Karl Overton and R. McCrindle. Parker's criteria for dipole forming aprotic solvents are a high dielectric constant (above 15) and the absence of labile hydrogen atoms capable of forming strong hydrogen bonds. Although he describes many others, most of his discussion is con- cerned with three such solvents: DMF, dimethylacetamide and DMSO. Properties