This new edition, the fifth under the aegis of the present editor, remains the one-volume source of factual information for chemists, both professionals and students—the first place in which to “look it up” on the spot. The aim is to provide sufficient data to satisfy all one’s general needs without recourse to other reference sources. A user will find this volume of value as a time-saverbecause of the many tables of numerical data which have been especially compiled.