This dictionary gives for a number of important organic compounds their commonest chemical names, structural and empirical formulas, approximate molecular weights, appearance, solubilities, melting or boiling points, and short bibliographies. It has been expanded from three volumes to four, because 2,500 compounds not included in the second edition have been added. When first sent to the printer the text was up-to-date through the end of 1950. Additional material was introduced during the period of printing so that for some compounds the information is complete through 1952. Like the earlier editions, this one is printed handsomely on good paper and is bound sturdily. No trade names are given, and since the references are to papers giving the best method of preparation and proof of structure, organic chemists will be the chief users of this dictionary.