Begin by going to Section 3 - Physical Constants of Organic Compounds. Substances are presented alphabetically by the primary name of the substance and given a number. You can choose one of the three indexes to find your substance: Synonyms, Molecular Formula (Hill Order: Carbon, Hydrogen, etc.), or CAS Registry Number. When you have selected your index, note the number of the compound. Then locate that number in the first part of Section 3. Find the data you need in the table. The chemical structure of the compound is also illustrated to help you identify the correct compound. The CRC tables rely on abbreviations; a complete list of appears on the introductory portions of the tables.