Chemical Abstracts in Print
(Available online for UC affiliates at SciFinder Scholar:

For literature published after 1947, the electronic SciFinder Scholar can be accessed at the Science Library. For literature published between 1907 and the 1940's the print index Chemical Abstracts (Ref QD1 C4) is available. CA currently indexes approximately 14,000 journals in all areas of chemistry and chemical technology, including chemical engineering and biotechnology. This handout is a guide to the Print Edition.

Abstracts are arranged in subject sections of each weekly issue. Through 1996 the coverage of the 80 sections was divided so that half of the sections are covered in alternate weekly issues. Beginning with 1997 all 80 sections are covered each week.

Chemical Abstracts can be approached by scanning the abstracts within the broad subject categories or by use of the indexes. The former method would be used mainly as a current awareness approach or when the subject area of interest is broad in scope; searching the literature by means of the indexes is the most efficient. The weekly issues have three indexes: keyword, numerical patent, and author. Ten or five-year Collective Indexes are available from 1907-1996, while between Collective Indexes six-month cumulations are issued. The Collective Indexes and the semi-annual indexes contain five different indexes: Author, Subject, Formula, Chemical Substance, and Patent. The Ring System and Registry Number indexes have been discontinued but can be useful for searching the older literature.

How to search

Each Chemical Abstracts (CA) index functions in the same manner. Under the index heading, a portion of the title for each article is given. The abstract number comes next; this refers the user to the actual abstract, including complete bibliographical information. For the five and ten-year cumulations, the volume and abstract number is given. For the six-month cumulations only the abstract number is given; the user must note which volume is covered and consult the corresponding volume number containing the abstracts.

  1. Searching by Author:
  2. Author indexes appear in each weekly issue and in each Collective Index from 1907.

    Where an author is not the first author of an article, reference must be made to the first author to obtain abstract number.

    Title of article by Steele. Complete citation is found in volume 120 of CA, abstract number 142658r

    Steele, G. Jr. See Kramer, R
    Steele, Glenn Jr. See Thomas, Peter
    Steele, Gregory Kent
    The prevalence of serum polychlorinated biphenyls
    and their association with blood pressure in a
    community environmentally exposed. 120:142658r
  3. Searching by Subject:
  4. Cumulative subject indexes are available from 1907. A keyword index appears in each weekly issue. Prior to 1972, the subject indexes included all chemical substances, but with the 1972-1976 cumulation, specific chemical substances are indexed in the Chemical Substances Index. The Subject Index does continue to refer to literature dealing with classes of chemical substances.

    Because of the complexity of chemical nomenclature and literature, an effective subject or chemical substance search requires the use of the Chemical Abstracts Index Guide, which has been published since 1967. (Shelved at the end of Chemical Abstracts, Ref QD1 C4). This tool is a cross-referenced guide which leads the user from a probable subject heading or chemical substance name to the heading or name actually used by Chemical Abstracts Service (CAS) in its indexes. If the desired entry does not appear in the Index Guide, then one can assume that the correct entry has been chosen. Prior to 1967, the user must rely upon cross-references found within the subject index.

    Cross reference in the Index Guide; articles on "xyloccoccus bicolor" are indexed under "arctospaphylos bicolor."

    When a registry number [843329-47-5] appears in the index guide, this is an indication that the entry will be found in the Chemical Substances index.

    Xylococcus bicolor
    Arctostaphylos bicolor

    2-Propenoic acid, 2-methyl-, esters,
       2-pyrrolidinone, 2-ethoxyethyl 2-methyl-2-
       propenoate, methyl 2-methyl-2 propenoate and 2-
       propenyl 2-methyl-2-propenoate [843329-47-5]

    Subject heading from 13th Collective Index

    Abstract number; number preceding the colon is the volume number.

    "R" indicates a review article.

    Pipes and Tubes
       High-strength steel, crane booms made of,
       High-strength steels for large pipes,
    122: R 35696w
  5. Searching by Formula
  6. The Formula Index is available from 1920. Formula indexes are not available in the weekly CA issues, but a cumulated index is issued every six months. Using this index is a fast way to locate references to a particular chemical substance. It also leads to the appropriate chemical names used in the Chemical Substance Index.
    Chemical formula & chemical name

    Registry number
    Abstract number; the "P" indicates that this reference is to a patent.

       Chromium, amminepentacarbonyl- (OC-6-22)-
    116: P 154913a; 118: 101261w, 261304r;
    120: 8740h; 123: 121893q
  7. Searching by Chemical Substance
  8. The Chemical Substance Index is available in the collective and semi-annual indexes from 1972 to the present. Chemical substances are also listed in the keyword index of the weekly issues. Prior to 1972, chemical substances are found in the General Subject Index. It is essential that the Index Guide be used when searching for chemical substances. (See example above in the subject search description.)

    Example from semi-annual Chemical Substance Index, Vol. 127, 1997

    Chemical substance index heading

    Subject subheading
    Subject description of content of the articles

    Abstract number

       3,7-dihydro-1,3,7-trimethyl- [58-08-2],
       biological studies
    antimicrobial effects of medicines which are not
          antibiotics, 30526v
    antiobesity compns. contg. dried orange peel exts.
          and caffeine, P 362477r
  9. Searching by Patent Number
  10. Chemical Abstracts covers a significant portion of world patents issued in the area of chemistry and chemical engineering. The Patent Index was first used in the 10th Collective Index, covering 1977-1981 and it also appears in each weekly issue. It replaces both the Numerical Patent Index (1935 through 1976) and the Patent Concordance (1963 through 1976). The Patent Index indicates the priority relationships between patent documents in a patent family and contains patent entries for both: 1) new patent documents processed during the period covered by that index and 2) patent documents processed during the period that are equivalent or related to patents abstracted earlier. Each time a new equivalent patent or related patent is referenced, a complete listing of all patent documents in the "family" of documents on the invention appears at the entry for the abstracted patent.

    Note that a patent is only listed once in Chemical Abstracts, to the first time it was indexed. Equivalents are not indexed. Thus the Patent Index is particularly useful to find out if a US equivalent exists for a foreign patent cited in the literature. This is convenient, since a US equivalent will be in English and more easily available than non-US patents.

    Example from semi-annual Chemical Substance Index, Vol. 127, 1997

    The abstract for German patent 19625912 appears in volume 126, abstract number 137814. Members of the patent family are listed.
    The codes A, A1, A2 have specific meanings for each country.
    DE 19625912 A1, 126:137814h
    FR 2736196 A1
    GB 2302670 A1
    JP 09/113698 A2
    US 5653830 A
    For US Patent 5681612, Canadian and Japanese patents were issued covering the same invention. The abstract covering the US patent is found in volume 127, abstract number 359651 US 5681612 A (Continuation-in-part), 127:359651n
    CA 2182495 AA (Related)
    JP 09/509105 T2 (Related)

    Numerical Patent Index (1935-1963):
    Up to 1963 all patents were abstracted and listed by number within countries with a reference to the CA abstract number. With the 7th collective index, CA published an abstract only for the first patent on any given invention; subsequent patents covering the same invention were listed in the patent concordance.

    Patent Concordance Index (1964-1976):
    Patents are listed by country. The concordance linked patents covering the same invention.

  11. Searching by Ring System
  12. The Ring Systems Index is helpful to determine the correct nomenclature to use when searching the Chemical Name Index. It is organized by the number, size, and atomic content of the component rings. Cumulative indexes of ring systems have appeared since 1916, but this index is not available in the weekly issues. The Index Guide to volume 76 includes a complete list of all the ring systems mentioned in CA during the period 1907 to 1971, up through the 8th Collective Index. Subsequent ring indexes were published in the first volume of the Formula Index section of the 9th, 10th, 11th and 12th Collective Indexes (covering 1972--1991.) The Ring System Index was discontinued with the 13th collective index (1992-1996).

    A related work is the Ring System Handbook and supplement (Ref QD390 R56.) Use it to determine the CA index name, structure, registry number, formula, and earliest citation to CA. It is also organized by the ring analysis, the number and size of component rings, and finally by elemental composition of the ring system.


  13. Searching by Registry Number

  14. The Registry Handbook is an outgrowth of CAS's computer system of automatically identifying chemical substances on the basis of structure and assigning a unique Registry Number to completely defined substances. The initial Registry Handbook lists the two million unique chemical substances registered during the period 1965-1971. Microfiche supplements cover the period from 1982-1986. The microfiche Chemical Abstracts Service Registry Handbook; Number Section: 1965-1986 Update also supplements the Registry Handbook. (both have call number M'fiche QD1 C4) Both these microfiche sets are shelved in the microforms area. This index has not been updated since 1986.

    When the registry number of a compound is known, its CA name and molecular formula can be determined by consulting the registry handbook. The Chemical Substance Index and Formula Index can then be used to retrieve information about the compound. The Registry Handbook and supplements have largely been superseded by the Registry file available online through CAS/STN.

Abstracts examples
The following illustrate a typical abstract for a journal article and a patent; these two sources constitute 95% of CA content.

CA abstract number
Title of Article
Bibliographic reference: journal title, date, volume, issue number, and pages.

Article is in English

128: 171810e The hydrolysis of di-isopropyl methylphosphonate in ground water. Sega, G.A.: Tomkins, B.A.; Greist, W.H.; Bayne, C.K. (Chemical and Analytical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA). J. Environ. Sci. Health, Part A: Toxic/Hazard. Subst. Environ. Eng. 1998, A33(2), 213-236 (Eng), Marcel Dekker, Inc. The half-life of di-iso-Pr methylphosphonate (DIMP) in groundwater at 10° was estd. 500 yr with a 95% confidence interval of 447-559 yr from measurements of the hydrolysis rates at 4 temps 70-98° . [Abstract continues…]
CA abstract number
Title of Patent
Patent number
Date patent was granted
127: 362477r Antiobesity compositions containing dried orange peel extracts and caffeine. Kishi, Masataka (Nonogawa Shoji Y.K., Japan) Jpn. Kokai Tokkyo Koho JP 09,295,932 [97,295,932] (Cl.A61K7/48), 18 Nov 1997, Appl. 96/135,924, 2 May 1996: 8pp. (Japan).
Antiobesity compns. for decompn. of fats and lipids, comprise dried orange peel exts. and caffeine. The compns. can be in bath prepns., makeups, lotions, tablets, powders, injections, and suppositories. [Abstract continues…]

The publication Chemical Abstracts Service Source Index, called CASSI, (Ref QD1 C3981, shelved on the turntable by the reference desk), may be used to obtain the full journal title for the abbreviations used by CAS.

Additional Information
For a more detailed guide to the use of Chemical Abstracts, consult Malcom Campbell's The Use of Chemical Abstracts (QD9 C36 1977) and From CA to CAS Online: Databases in Chemistry by Hedda Schulz and Ursula Georgy (QD9 S3813 1994). For an explanation of the subject sections, consult the Subject Coverage and Arrangement of Abstracts by Sections in Chemical Abstracts, 1987 edition (Ref. QD9 A46 1987, shelved with the Index Guide.)

Last modified: 2/5/2009 12:45 PM by J. Mason