Although conceived originally as a textbook, it rapidly became apparent that the industry also wanted or needed this book. Accordingly, succeeding editions have been aimed more and more toward providing a survey of the industry’s engineering practices. International interest is being recognized in this Fourth Edition by the introduction of more information on foreign crude oils and more complete information on the evaluation of oils. New Appendix B of the Fourth Edition introduces the analyses of over 70 foreign crude oils as well as about 90 representative United States oils for comparison.