THE LABORATORY EVALUATION OF PROPHYLACTIC DENTIFRICES 491 THe. LECTURER: Not by us. The electron micrcgraphs (Figs. 4-11) were taken at an early stage of the development of a fluoride toothpaste. We have done chemical studies on the action of monofluorophosphate on hydroxyapatite which showed that the fluorophosphate ion seems to be incorporated into surface enamel.

Book reviews OIL, DETERGENTS AND MAINTENANCE SPECIALTIES. Vol. 1. B. Levitt. Pp. vii q- 280 q- Ill. (1967). Chemical Publishing Co., New York. $13.75. The emphasis of this book is in the basic practical application of knowledge acquired by the author over many years of experience in the manufacture of oils, soaps and detergents. The book in many ways resembles E. T. B•ebb's classic work Soaps and Glycerine Manufacture in which the same subjects are presented in a similar lucid manner devoid of excessive theoretical and technical discussion. It is very easy in this type of informative writing to become sidetracked by the hundreds of excellent scientific specialist papers which can only distract without satisfying the reader's interest in the main issues involved. The author has fortunately avoided these pitfalls, and each chapter is dealt with in a masterly and facile style, which can readily be followed by semi-technically trained personnel. The book is divided into nine chapters comprising the Introduction, Animal Fats and Oils, Vegetable Fats and Oils, Fatty Acids, Fatty Alcohols, Glycerol, Surfactants and Surface Activity, Production of Fats and Oils, Soap Manufacture, Synthetic Detergents, and finally Analysis of Oils and Detergents. The second chapter deals concisely with the rendering of animal fats for soap making and the refining of fish oils such as herring, menhadden, salmon, pilchard and sardine oils for use in paint, linoleum and printing ink industries. The thera- peutic values of the fish liver oils, followed by butter, margarine, Janolin and its derivatives, sperm oil and spermaceti and their applications are fully discussed. The third chapter deals in like manner with about twenty of the better known vegetable oils and fats finalised in a chemical and physical constants table of 76 oils and fats each with their sources of origin. Fatty acids, alcohols, and glycerol, their synthesis, characteristics and uses, are treated effectively in chapter four, followed by surfactants and surface activity and the importance of biodegradability of detergents in chapter five. The production of fats and oils solvent extraction, continuous centrifugal refining, Solexol, Furfural, and Emersol processes, followed by a description of hydrogenation, sulphonation, the fat splitting processes and the production of glycerol, concludes an interesting and factual sixth chapter. Perhaps the most important chapters in the books are the 7th and 8th which deal fully with the various aspects of soap and detergent manufacture which hold a mass of facts, figures and formulations most useful to the technician or chemist working in these fields. L. CHALMERS. 493