Stanford University Libraries

Chemical Literature (Chem 184/284)
University of California at Santa Barbara

Lecture 9: Chemical Abstracts in Print, Part 1

Chemical Abstracts Service:

  • Chemical Abstracts Service was founded in 1907 as a division of the American Chemical Society.
  • The first volume contained 15,000 abstracts and was distributed free of charge to ACS members.
  • Today: about 700,000 abstracts per year; annual subscription—over $15,000.

What CAS Does

  • CAS attempts to comprehensively index the chemical literature, including:
    • some 8–12,000 journals; 1,300 of which are now indexed cover to cover—covering documents of chemical importance
    • patents from 28 nations and two international organizations
    • technical reports, conference papers, books and dissertations.
    • electronic journals

Other CAS Services

  • Chemical Industry Notes (CIN) — indexes the literature of chemical business (e.g. Chemical & Engineering News, Chemical Week)
  • CAS Registry Service
    • Started to track chemical substances for CAS internal files; now the standard method for uniquely identifying chemicals, used as an indexing tool by many chemical reference sources.
    • All substances indexed by CAS get RN’s, plus substances submitted by outside firms or agencies.
    • Every chemically distinct substance gets its own Registry Number, including stereoisomers, isotopically labeled substances, mixtures, etc.
    • Registry Numbers are of the form: xxxxxx-xx-x. The number of digits in the first group may vary, but the second and third groups are always two digits and one digit.
    • The Registry Number has no chemical meaning; you can’t tell from the RN what kind of compound it refers to.
  • Chemical Abstracts Service Source Index (CASSI)
    • Lists all periodicals ever indexed by CAS
    • Lists many pre-1907 sources, such as those appearing in Beilstein
    • Available in print or on CD-ROM
    • Periodicals are listed in alphabetical order by their abbreviations — the name appears in full, with the abbreviated portion in boldface.
    • Listings include language information, starting dates and current volume numbers, cross-references to changed titles or translations and holdings information.
  • CAS Document Detective Service
    • provides copies of documents indexed by CA or CIN, generally for the past 20 years.
    • Exceptions: indirectly indexed documents, like tech reports or dissertations
    • If copyright is a problem, they will lend the original.

Importance of Chemical Abstracts

Analyzing Chemical Abstracts in terms of the general properties of indexes:

  • Scope
    • CA attempts to cover chemistry in the broad sense…anything that might be interpreted as new research in chemistry or chemical engineering
    • Chemistry as the “central science”. CA’s coverage has high overlap with medicine, biology, physics, materials, agriculture, geology, etc., making it important for researchers in those fields as well.
    • Note: since CA focuses on “new research” in earlier times it did not index all chemical patents—only those deemed to have “new chemistry”.
  • Comprehensiveness
    • CA attempts to cover the literature of chemistry worldwide, in any language.
    • It attempts to cover all forms of primary chemical literature.
    • Note that in some cases—technical reports and dissertations—it depends on secondary sources and indexers do not read the original documents.
  • Chronological coverage
    • Print CA began in 1907; electronic CA in 1967 (although there is some progress toward converting the 1907–1966 abstracts to electronic form.)
    • Abstracts are added to the print sections every week; in online form, updates are daily.
    • Print abstracts get keyword indexing when published; detailed indexing when a volume is completed and indexes are cumulated every ten volumes. Electronic abstracts have detailed indexing when they are added to the database.
  • Access points
    • Weekly issues index by author, keyword and patent number (see below for details.)
    • Volume indexes index by author, subject heading, systematic chemical name, molecular formula and patent number (see below).
    • Electronic forms combine keyword and subject heading approaches, and add roles for chemical substances.
    • Links to Registry File add enhanced searching of chemical substances, including structure searching.
  • Constant enhancements: CAS has been in forefront of computerization of indexing for over 30 years and is always refining its search tools.

Chemical Abstracts in Print: Arrangement of Abstracts

  • For ease of browsing, abstracts are grouped by subject area.
  • Currently there are 80 subject sections, divided into five broad groups.
    • Biochemistry
    • Organic Chemistry
    • Macromolecular Chemistry
    • Applied Chemistry and Chemical Engineering
    • Physical, Inorganic and Analytical Chemistry
  • Biochemistry and Organic Chemistry used to come out in odd-numbered weeks. Macromolecular Chemistry, Applied Chemistry and Chemical Engineering and Physical, Inorganic and Analytical Chem. used to come in even-numbered weeks. Now, abstracts are added in all sections each week.
  • Cross-references are used where a given abstracts might legitimately appear in more than one section.
  • Note that subject sections change with time to reflect current research.
  • Subject Coverage Manual gives a detailed definition of each section, and a table of changes over the years.

Contents of the Abstract Record

  • All CA records contain:
    • Title of the document
    • Author(s) or inventor(s) for patents
    • Corporate source or patent assignee information
    • Source Information, e.g. journal title, volume, issue, pages or patent numbers
    • Language
    • Abstracts (usually)
  • Author’s names appear as given in the original document.
  • Abstracts for journal articles are usually those written by the author.
  • Patent abstracts may be fleshed out by the indexer.
  • Dissertations and some other documents have no abstracts.


  • Journal names are listed using CASSI abbreviations.
  • Corporate names are heavily abbreviated.
  • All abstracts use abbreviations for common chemical terms (see CAS Standard Abbreviations and Acronyms at

Indexing in Print CA

  • The types of indexing available in CA reflect the constraints of print.
  • The indexing available in the weekly issues is that which can be done most quickly.
  • The indexing in the Volume and Collective Indexes is more systematic, but still reflects the limitations of print.
  • Issue Indexes
    • Author
    • Keyword
    • Patent
  • Volume & Collective Indexes
    • Author
    • Chemical Substance
    • General Subject
    • Molecular Formula
    • Patent

Author Indexing

  • Weekly Issues
    • All authors are listed by last name and initials only. The index gives only the abstract number. Examples:
      • Lipshutz B H 151869t
      • Little R D 152780u
    • Patents have entries for both inventor and assignee; their abstract numbers have P before the number. Examples:
      • Genentech, Inc. P146735s
      • Leong S R P 146735s
    • Other types of corporate authors, such as societies and government agencies, also get author entries
      • United States Food and Drug Administration 150996v 150997w
  • Volume and Collective Indexes
    • First authors get both the abstract number and title of the paper listed under their names.
    • The author name is not necessarily the form used in the article, but may be a standardized form of the name.
    • Other authors are cross-referenced to the first author of the document.
    • Examples:
      • Ford, Peter Campbell
        Quantitative mechanistic studies of the photoreactions of… 148754a
      • Lange, Frederick Fouse
        See Miller, Kelly T.; Sudre, Olivier
        ---; Lam, D.C.C.; Sudre, O.
        Powder processing and densification of ceramics 144196x
    • Even though CA tries to pull all of an author’s works under one name, it cannot always distinguish authors with the same initials, so it alphabetizes by last name and initials, even where the full name is spelled out! Examples:
      • Ellis, A.
      • Ellis, Arthur Baron
      • Ellis, A. D.
      • Ellis, Anthony Ewart
      • Ellis, Avery K.
      • Ellis, Andrew Michael
      • Ellis, Albert T.
  • Spelling of Author Names: Be aware of special rules for handling certain names. Names with “Mc” or umlauted letters or transliteration from non-Roman alphabets can be tricky. Example:
    • Mössbauer is listed as Moessbauer

Patent Indexing

  • Chemical Abstracts only indexes the first version of each patent it receives.
  • However, the patent index (arranged by country code and patent number) gives cross-references from later, equivalent patents, that is, the same invention by the same inventor, patented in a different national or international patent office.
  • When searching for an equivalent patent, start at the year of issue of the known patent reference and work forward until you find the equivalent or run out of indexes.

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