PHYSIOLOGICAL PROPERTIES OF PROPELLANTS 351 CONCLUSION This paper does not claim to be a complete summary of all tests with propel/ants, both published and unpublished. Nevertheless, the information presented is sufficient to draw the proper conclusion. All tests yielded identical results and there is thus no necessity to start further tests. Pro- pellants 11, 12, 114, propane/butane and vinyl chloride, used in the aerosol industry, have a varying, but generally low or very low toxicity. The con- centrations by volume formed when using a pressurized dispenser are normally not only completely nontoxic, but are considerably lower than, or near, the MAC-values. It is true that no tests have been carried out with propane/butane, but their chemical structure permits this analogous conclusion. Actual practice confirms the good skin compatibility and the safe inhalation of the named propel/ants. A billion pressurized dispensers each year indicate the accuracy of the described tests. The problem of the thermal decomposition should not be exaggerated. Here, too, actual prac- tice has shown that this danger is very small. From the physiological point of view, therefore, the pressurized pack, i.e. the propellant utilized, may be regarded as safe. (Received: 2nd February 1965) REFERENCES Reed, F.T. Am. Perfumer Aromat. 75 40 (October 1962) Downing, R. C. and Madinabeitia, D. Aerosol Age 5 25 (September 1960) Ullmann, Enc. der technischen Chemie 5 489 (1954) (Urban und Schwarzenberg Verlag, Manchen) Schade, H. Private commu•.ication (1956) Torkelson, T. R., Oyen, F. and Rowe, V.K. Am. Ind. Hyg. Assoc. J. 22 854 (1961) Schade, H. Private communication (1960) Shepherd, H. R. Aersols-Science and Technology 374 (1961) (Interscience Publishers, Inc., New York) Hofmann, B. Deut. Farben-Z. 10 387 (1956) Scholz, J., in Blackel, H. Fortschritte der biologischen Aerosolforschung 1957-1961 Nord. Hyg. Tidskr. 3 ½) 11 (1958) Quevaville, M. A., Garcet, S., and Garcet-Pottier, J. Ann. pharm. fran•. 17 430 (1955) Griebel, Private communication (1956) Griebel, Private communication (1959) Griebel, Private communication (1959) Simon, Private communication (1960) Friedrich, H.C. Private communication (1960)

352 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS BOOK REVIEWS The Principles and Practice of Modern Cosmetics. Volume 1. R. G. Harry. MODERN COSMETICOLOGY. Fifth Edition. Revised by J. B. Wilkinson, and R. Clark, E. Green and T. P. McLaughlin. Pp. xxiv q- 683 q- ILl. (1962). Leonard Hill (Books), Ltd., London. 84s. Few cosmetic chemists can be unfamiliar with Harry's "Modern Cos- meticology" and have not found this volume of some assistance in their work during the twenty-two years since the first edition was published. The need for a fifth edition reflects not only the tremendous advances in cosmetics technology but also the sound basis on which the book is written. The revision has been undertaken by a team of leading workers in cosmetics technology who chose to retain the original basically sound frame- work. At first glance, the fifth edition appears to differ very little from the previous one but closer reading reveals how much thought and work has gone into this new edition. Four chapters have been omitted: On toilet soap--impossible to deal with adequately in a book of this size, and those on diet and skin health, cosmetic stockings, and cosmetic facts and fallacies. A new chapter on "Pressurized Packs" surveys adequately the technical aspects of the aerosol package. Practically every chapter has been revised in some degree but because of changing ideas and importance, some chapters have come in for more drastic changes than others. The basic framework of the book has been retained and the treatment of Chapter 1 "The Skin" illustrates the general pattern of the revision. Much detail of lesser importance has been omitted and the nucleus of basic information rearranged, revised and expanded where necessary to give a sound, logically developed and highly readable account of the basic facts every cosmetic chemist should know about the skin. Chapters 16 "Dentifrices", 21 "Hair Shampoos", 22 "Permanent Waving", 24 "Hair Dressings and Conditioners", 25 "Hair Dyes" and 28 "Antiperspirants and Deodorants" have all largely been rewritten to in- corporate recent developments and ideas. The index is shorter than that in the previous edition and yet seems more comprehensive, indicating the care and selectivity exercised in its preparation. The revisers have done a splendid job and produced a new work which at times differs not so much in the actual information contained therein but in its arrangements, and therefore in the ease with which it can be read and absorbed and a given piece of information found when required.