This book is not intended to be a basic text in infrared spectroscopy. Many such books exist and I have referred to them in the text. Rather, I have tried to find applications that would be interesting to a variety of people: advanced undergraduate chemistry students, graduate students and research workers in several disciplines, spectros- copists, and physicians active in research or in the practice of medicine. With this aim in mind there was no intent to have exhaustive coverage of the literature. I should like to acknowledge my use of several books and reviews, which were invaluable in my search for material: G. H. Beaven, E. A. Johnson, H. A. Willis and R. G. 1. Miller, Molecular Spec- troscopy, Heywood and Company, Ltd., London, 1961. J. A. Schell man and Charlotte Schellman, 'The Conformation of Polypeptide Chains in Proteins," in The Proteins, Vol. II, 2nd Ed. (H. Neurath, ed.), Academic Press, New York, 1964. R. T. O'Connor, "Application of Infrared Spectrophotometry to Fatty Acid Derivatives," J. Am. Oil Chemists' Soc. 33, 1 (1956). F. L. Kauffman, "Infrared Spectroscopy of Fats and Oils," J. Am. Oil Chemists' Soc. 41,4 (1964). W. J. Potts, Jr., Chemical Infrared Spectroscopy, Vol. I, Techniques, Wiley, New York, 1963. R. S. Tipson, Infrared Spectroscopy of Carbohydrates, National Bureau of Standards Monograph llO, Washington, D.C., 1968. C. N. R. Rao, Chemical Applications of Infrared Spectroscopy, Academic Press, New York, 1963.