The Use of Indexes - ACS Publications

The Oxford Dictionary and Webster's have practically the same definition for the word "index" ..... the diethyl ester of malonic acid is found under C...
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The Use of Indexes G. J . C. POTTER Pulp and Paper Research Institute of Canada, Montreal,

Canada

FRED J . BASSETT

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The Upjohn Co., Kalamazoo,

Mich.

As the index is the key to the information con­ tained in a publication, its proper use is of para­ mount importance. This is particularly striking with regard to abstracting and indexing periodi­ cals which have elaborate indexes based on their own systems. Effective use of the subject, author, and patent indexes of Chemical Abstracts, British Abstracts, Chemisches Zentralblatt, Bulletin de la Société Chimique de France, Biological Abstracts, Applied Science & Technology Index, and Engi­ neering Index is demonstrated with their distinc­ tive features and systems. The Richter and Hill systems of formula indexing are explained and discussed as used in Chemical Abstracts, Chem­ isches Zentralblatt, Beilstein, and Richter-Stelzner. Examples of arrangement of formulas, inclusive coverage dates, and hints in using formula indexes are given.

T h e Oxford Dictionary and Webster's have practically the same definition for the w o r d "index" used as a guide to information—viz., " a n alphabetical list, usually at the end of a book, of the names, subjects etc., occurring i n it, w i t h indication of the places where they occur." This definition is elementary, and though it m a y be applicable to books i n general literature, it is only partially applicable to technical textbooks, w h i c h index to a greater extent than that. Still less applicable is it to such a n abstracting periodical as Chemical Abstracts or an annual index like the Engineering Index. T h e index appearing i n each of these is verily a key to the literature each covers rather than just " a n alphabetical list of names, subjects, etc." It is more than a key, as, w i t h each subject heading, there are cross references not only to synonymous terms but also to cognate subjects, instructing the searcher as w e l l as aiding h i m to obtain the information desired. I n consulting these indexes to obtain references on some specific subject, the searcher is also able to observe 23 SEARCHING THE CHEMICAL LITERATURE Advances in Chemistry; American Chemical Society: Washington, DC, 1961.

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ADVANCES IN CHEMISTRY SERIES

the scope of information available on the subject—an observation w h i c h w i l l serve h i m i n good stead i n the future. It is necessary to understand the use of indexes i n order to make a thorough literature search i n the least possible time. T h e necessity of this understanding is acknowledged by Beveridge ( 3 ) , who states, "Students need some guidance i n ways of tracing references through indexing journals and catalogues and i n using libraries." This remark is equally applicable to the neophyte i n literature search­ ing as an occupation, since i n few university curricula is a course i n literature searching included. I n addition to understanding h o w to use an index, a knowledge of different indexes is important, as, included i n the time and thoroughness factors, is the consideration of consulting the index most appropriate to the purpose of the search. F o r example, i n looking for information on chemical equipment it may be timesaving to consult the Engineering Index rather than Chemical Abstracts, par­ ticularly as the index entries i n the former are classified and abstracted descrip­ tively. A g a i n , if one is seeking the title of a paper on a certain substance, it is best to consult the Applied Science &• Technology Index (prior to 1958 the Industrial Arts Index) first, as references are given b y titles of papers, whereas the references i n Chemical Abstracts are for the most part to information contained i n a paper. These isolated examples i n no way detract from the fact that Chemical Abstracts is best consulted first for the most part because of the excellence of its index. I n consulting an index, the searcher of course has his part to play. H e must not be disappointed if he does not find the subject heading he uses on his first approach. Accordingly, the searcher should select words or w o r d i n g synonymous w i t h the first subject heading he has i n m i n d or, if possible, the proper chemical name of the subject heading. H e w i l l then be sure to find one of these headings i n the index. Smith (19) draws the searchers attention to this, and the introduction to the annual index of Chemical Abstracts states, " F o r the best results i n the use of an index the user must meet the index maker part of the w a y i n an under­ standing of the indexing problem and, i n particular, of nomenclature." Chemical Abstracts is most helpful i n supplying synonymous headings, w h i c h are listed w i t h a "see" reference to the heading under w h i c h the references are entered. F o r example, synonymous terms given for " f u r f u r a l " are "furfuraldehyde, furfurole, fural, 2-furaldehyde, furole" and the references are listed under "2-furaldehyde." British Abstracts on the other hand lists all references to this compound under "furfuraldehyde" w i t h no cross references, and does not list synonymous terms. Chemisches Zentralblatt lists "furfural, furfuraldehyde and f u r f u r o l " w i t h refer­ ences under " f u r f u r o l . " It is also important for the searcher to understand the wording of the refer­ ence entries, for these vary from one index to another, as pointed out b y Singer (18), w h o shows differences i n spelling and i n the common meanings of words i n British and American usage. Chemical Abstracts has some distinctive wordings— for example, "detection o f is the equivalent of "qualitative determination of," including "tests for" and "reaction for." Hence some discretion must be observed in interpreting reference entries. Subject Index T h e subject index is the most important part of the index and the searcher should make himself familiar w i t h the system of subject indexing used b y indexing periodicals. SEARCHING THE CHEMICAL LITERATURE Advances in Chemistry; American Chemical Society: Washington, DC, 1961.

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POTTER AND BA5SETT

Indexes

25

L e t us first consider the subject index of Chemical Abstracts, the most reveal­ ing of the chemical indexes. Some idea of the indexing system is given i n the introduction to each annual index, but the system is fully explained i n the 1945 issue (6). The first consideration is that subject indexing is used rather than w o r d indexing. F o r instance, a book entitled "Chemists' H a n d b o o k " w o u l d be word-indexed under " C h e m i s t " but subject-indexed under "Chemistry," if the subject matter were chemistry rather than chemists. Another book on "Who's W h o i n Chemistry" w o u l d be word-indexed under " C h e m i s t r y " but subject-indexed under "Chemists." Another guiding principle to the CA index is that of inversion, whereby the subject is usually the chemical substance of w h i c h the compound is a derivative. F o r instance, "trinitrobenzene" is indexed as "Benzene, 1,3,5-trinitro-" and not as "Trinitrobenzene," though there may be a reference such as "Nitrobenzene, see Benzene, nitro-." Compounds that have common names are listed under their common as well as their chemical names, but the reference entries may be made under either. F o r example, styphnic acid has the chemical name 2,4,6-trinitroresorcinol, but the index entries are under styphnic acid w i t h a cross reference to Resorcinol, 2,4,6trinitro-, see Styphnic acid. O n the other hand, the well-known insecticide D D T is listed w i t h a "see" reference to its chemical name and the reference entries are under the latter, "Ethane, l , l , l - t r i c h l o r o - 2 , 2 - b i s (p-chlorophenyl)." In general, it may be said to be the exception, not the rule, for the common name of a com­ pound not to be listed. A l l names, common and chemical, are listed alphabetically. T h e entries under headings i n Chemical Abstracts describe the information contained i n the abstracts w i t h the page on w h i c h the abstract occurs; the entries are not the titles of papers. These entries are again arranged alphabetically, but prepositions and articles are not considered i n this arrangement. Careful con­ sideration must be given to the w o r d i n g of these entries, to be certain no perti­ nent reference is missed. W o r d i n g is used that w i l l give as m u c h guidance as possible w i t h the m i n i m u m of words. Successive entries are made i n line under each other, but w h e n entries are indented they include the w o r d under w h i c h the indentation is made. The system of subject indexing i n British Abstracts [which ceased publication w i t h the December 1953 issue] is described i n the 1948 index (4). Subject index­ ing is used rather than w o r d indexing, but the range of subject headings listed is very m u c h narrower than that of Chemical Abstracts. These subject headings or key words do not always include the chemical name but are "the words under w h i c h the information is most likely to be sought." Sometimes cross references to synonymous terms and cognate subjects are given and sometimes not; the example of furfural has been mentioned. F a r more use is made of adjectives i n the alphabetical arrangement than i n Chemical Ab­ stracts, w h i c h prefers nouns. "Catalytic hydrogenation," for instance, is listed w i t h "catalytic" as the key w o r d i n the alphabetical arrangement, whereas i n Chemical Abstracts it is listed w i t h subject heading "catalysts" and subheading "for hydrogenation." T h e reference entries under the subject headings follow the pattern of Chemical Abstracts, except that prepositions like " f o r " and " i n " follow the alpha­ betical arrangement, though their use is restricted as m u c h as possible. Prefixes like cycle--, iso-, di-, etc., are written i n italics and are not included i n the alpha­ betical arrangement, unlike Chemical Abstracts, w h i c h includes them. Again, these entries must be carefully read. SEARCHING THE CHEMICAL LITERATURE Advances in Chemistry; American Chemical Society: Washington, DC, 1961.

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T h e index of Chemisches Zentralblatt has been described by Spitzer (20), but a few of its essential features may be mentioned here. T h e index is classified w i t h main subject headings i n heavy black type, subheadings i n smaller black type, and other headings under these i n yet smaller black type. F o r instance, "chlor" (chlorine) is i n large heavy black type, "chlorverbindungen" (chlorine com­ pounds) is a subheading i n smaller black type, and "chlorwasserstoff" (hydro­ chloric acid) is a subheading to "chlorverbindungen" i n yet smaller black type. A s i n the case of furfural, several synonymous names may be listed but, w h e n not listed, they must be found under the larger type headings, so that one must know i n w h i c h of these headings or subheadings the desired information is to be found. A unique feature of this index is that sometimes a substance is listed w i t h a "see also" reference to its formula i n the formula index, where the reference entries to the pages of the abstracts are to be found. U n l i k e Chemical Abstracts and British Abstracts, the reference entries are of the " r u n n i n g " type, one following another on the same line, not a separate line for each entry. In all entries, of course, the arrangement is for the most part alphabetical but, as i n British Abstracts, prefixes like iso-, t r i - , etc., are disregarded. T h e Engineering Index is on a par w i t h Chemical Abstracts for including w i t h subject headings a list of synonymous terms and cognate subjects. The headings are classified w i t h subheadings, and under each heading or subheading descriptive abstracts of the reference papers are given. U n d e r the subheadings there are also "see also" references to synonymous terms and cognate subjects. T h e headings are, like those of British Abstracts, those words under w h i c h the i n ­ formation is most likely to be sought. A valuable feature of the index is that short descriptive abstracts of books are included. This index is most useful for giving information pertaining to applied chemistry, particularly any chemical operation i n w h i c h engineering plays a b i g part—for example, the "see also" references to the heading " C h e m i c a l Processes" are comprehensive. T h e headings, subheadings, and titles of papers abstracted are arranged alphabetically. I n the titles, preposi­ tions and articles are not included and titles of foreign papers are given i n the original language. T h e Applied Science &• Technology Index has its particular uses and is m u c h favored by, and most useful to, those who have no chemical training. It gives literature references to substances and processes, and it is useful for collecting references to papers on a certain subject, especially if authors' names are not known. Headings may be also said to be those under w h i c h the information is most likely to be sought and, for the most part, words or wording i n common use. F r o m the chemical point of view, however, the literature it covers is restricted. Its great value lies i n giving references to new items, and business and marketing information. It also describes several magazines w h i c h are not w e l l known. The index of Biological Abstracts contains headings for w h i c h the majority of searchers w o u l d look. C h e m i c a l compounds are not indexed i n accordance w i t h chemical nomenclature but b y their common names. T h e same applies to drugs. Substances of interest to biologists, such as individual insecticides, plant hormones, etc., are listed under headings corresponding to their usage. T h e indexing system is described i n a f e w pages immediately before the subject index. Author Index In most indexes the names of authors are arranged alphabetically. " M c , " however, is usually treated as " M a c " and interfiled. Names beginning w i t h " d e " SEARCHING THE CHEMICAL LITERATURE Advances in Chemistry; American Chemical Society: Washington, DC, 1961.

POTTER AND BASSETT

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and " v o n " are indexed under " d " and " v , " or cross-referenced to the index entry used. Chemisches Zentralblatt, however, does not consider " v o n " i n the alphabetical arrangement. Spellings of authors' names generally are those given i n the papers. In some instances, however, there is confusion i n names, especially i n transliterat­ ing from C y r i l l i c and other script. T h e author index is particularly of value i n tracing the papers an author has published, as the titles of the papers are given after his name, w i t h the page refer­ ence to the abstract. I n general, when there are two or more authors to a paper, the title of the paper is given under the name of the first author.

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Patent Index Chemical Abstracts, British Abstracts, a n d Chemisches Zentralblatt have patent indexes i n w h i c h the numbers of the patents, issued i n different countries and abstracted b y them, are listed w i t h the page of the abstracts o n w h i c h they appear. W h e n the number of a patent is known, finding an abstract of that patent presents no difficulties. In searching for patents on a certain subject, the index is used as i n searching for information on any subject. I n British Abstracts and Chemical Abstracts the reference entries under subject heading concerning patents are prefixed b y the letter " P , " and i n Chemisches Zentralblatt they are marked w i t h a n asterisk. T h e same prefixes are placed before the titles of patents i n the author index, w h i c h also lists the names of the assignee. I n Chemisches Zentralblatt the name of the country i n w h i c h the patent was first issued is included after the title of the patent i n the author index. Formula Index There are two systems of formula indexing i n common use today, the H i l l and the Richter systems. In the original H i l l system (11) formulas are written i n strict alphabetic order, omitting water of crystallization, except that w i t h carbon compounds carbon is written first, followed immediately b y hydrogen if present—i.e., trichloropropanol, C H C 1 0 . E a c h compound is arranged i n the index b y its o w n formula; the sodium salt of propionic acid, C H ' N a 0 2 , is entered as such. T h e H i l l system is used i n modified f o r m today b y Chemical Abstracts and Referativny Zhurnal, Khimiya (17) and indexes both inorganic and organic com­ pounds. Beilsteins H a n d b u c h (2) formula index to the second supplement uses the H i l l system. This index covers the original work and two supplements. In the modified H i l l system as used by Chemical Abstracts today the arrange­ ment of symbols i n formulas is alphabetic, except that i n carbon compounds C always comes first, followed immediately b y H if hydrogen is also present. F o r deuterium and tritium compounds, D and T , respectively, are used. These are placed alphabetically i n formulas; the exception i n arrangement made for H is not extended to include these isotopes. G l u t a m i c - d acid is therefore written C H DN0 . T h e names of certain elements and their respective symbols are given preference over former names. T h e preferred names are astatine, beryllium, niobium, hafnium, and promethium (but not wolfram) (7). T h e arrangement of formulas is also alphabetic, except that the number of atoms of a specific k i n d influences the order of listing. A l l formulas w i t h one car3

5

3

3

5

8

5

4

SEARCHING THE CHEMICAL LITERATURE Advances in Chemistry; American Chemical Society: Washington, DC, 1961.

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ADVANCES IN CHEMISTRY SERIES

bon atom only come before formulas with C —thus, C F , C H F I , C H N O , C O , C Z r , C HF , C H F . Compounds are not always formula-indexed under their own formulas. This is a departure from the ideal, but is reasonable. The interest i n a salt of a com­ plex organic acid is likely to be mainly in the acid.. It is more valuable to have the record of the salt under the formula of the acid for the use of searchers looking u p the acid. I n Chemical Abstracts entries under their o w n formulas are made for all strictly inorganic and strictly organic compounds, both addition compounds and true reaction derivatives (esters, acetals, hydrazones, oximes, picrates, semicarbazones, etc.); the diethyl ester of malonic acid is found under C H 0 . Inorganic salts of organic acids and inorganic addition compounds of organic compounds (hydrohalides, perchlorates, sulfates, etc.) are not given separate entries but are indicated i n modifying phrases under the formula of the compounds from w h i c h they are derived (under the acid i n the case of a salt). Salts of formic, acetic, and oxalic acids are exceptions; these are entered under their o w n formulas, and lithium acetate is found under C H L i 0 . T h e arrangement of entries under any formula heading is alphabetic accord­ ing to the preferred names of the isomers. Isomerism is not indicated i n the formula index i n cases i n w h i c h the names differ only i n position numbers or letter; 2- and 3-pentanone are both indexed under C H O , pentanone. Polymers having different names and recognized as different substances are all entered under their accepted formulas. B u t a definite compound for w h i c h different polymeric formulas are i n use is entered under the simplest formula, as C l F e for iron chloride. 2

2

3

2

2

2

2

2

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7

2

3

] 2

4

2

5

1 0

3

In the case of labeled compounds, entry is normally without special designa­ tion i n the formula, but name entries under such formulas show the labeled nature of the compound; C H 0 , i s o b u t y r i c - l - C acid, indicates that the number one carbon atom is labeled. Deuterium and tritium compounds show labeling i n the formula index, as C H D O , methanol-d, or C H D 0 , acet-d -aldehyde. The formula index only of Chemical Abstracts lists new compounds for w h i c h no names or structures have been given i n the original literature. Entries under a formula heading consist of the formula, i n bold-faced type; the name as it has been used i n the subject index, i n lightface roman type—that part of the entry i n this type is the exact equivalent of the formula given; occa­ sionally a m o d i f y i n g phrase or w o r d i n italics w h i c h represents that part of the compound indexed not represented in the formula, as " N a salt" or " d i - H C l " ; and the column-fraction reference to the abstract proper. 4

8

14

2

3

2

2

2

2

Cross references to the subject (primary) index are used for many simple inorganic compounds: A1C1 , see A l u m i n u m chloride; a l l minerals of definite composition, F M g N a 0 S i , see Richterite; and the more common organic com­ pounds, C H 0 , see F u r a n . 3

2

4

6

2

2 2

8

4

Water of hydration, omitted i n the formula when indexed, is often given i n lightface type following the formula, as A s H 0 Z n . H 0 , Zinc arsenate. 4

2

T h e Richter system, devised for organic compounds only, was formerly used in modified form by Beilstein ( I ) and Chemisches Zentralblatt. In this system carbon always comes first, followed by the other elements i n an arbitrary arrange­ ment termed the chemical alphabet—e.g., H , O , N , C I , B r , I, F , S, P—and the re­ maining elements i n alphabetic order: A — Z , of their symbols. Beginning w i t h the 1956 formula index, Chemisches Zentralblatt adopted the H i l l system of indexing (15). The formula index to the second supplement of Beilstein changed to the H i l l SEARCHING THE CHEMICAL LITERATURE Advances in Chemistry; American Chemical Society: Washington, DC, 1961.

POTTER AND BASSETT

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Indexes

system at the same time (2). This index covers the original and first supplement material i n addition to the second supplement. The arrangement of formulas within the index b y the Richter system may be termed a semiclassified order, depending o n :

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1. T h e number of carbon atoms 2. T h e number of other elements w h i c h , i n addition to C , are contained i n the compound 3. T h e k i n d of elements (which i n addition to C are contained i n the mole­ cule) i n accordance w i t h the chemical alphabet stated previously 4. T h e number of atoms of each element w h i c h , i n addition to C , is contained i n the compound Water of crystallization is not made a part of the formulas indexed. According to this arrangement all compounds containing one carbon and one other element i n any proportion are listed before compounds containing one carbon and two other elements i n any proportion. II

III CH CH CCU CS

1III

CHCL CH CH 0 CH C1 CCLBr

2

4

2

CHONMg CH ONBr CH ON Cl CH5O4NS

2

2

2

1IV CH0 C1 CHNS CH 0 S CH ON CtLOMg

2

2

3

2

2

3

3

2

A t the top of each page of a l l publications using the Richter system w i l l be found A r a b i c and Roman figures serving as searching aids. T h e A r a b i c figure denotes the number of carbon atoms i n the formulas listed on the page; the Roman figure denotes the number of other elements combined w i t h carbon. In the third edition of Richter's formula index (16) each compound has only one place i n the compilation, w i t h the exception of the salts, w h i c h are placed w i t h the compounds from w h i c h they are derived. T h e chlorides, bromides, iodides, and cyanides of quaternary ammonium bases, however, are entered under the parent compound. Polymeric compounds w i t h fixed molecular weights are entered under their o w n formulas—e.g., ( C H O N ) , cyanuric acid, is found under 3III, C3H3O3N3. Certain modifications of the Richter system have been made i n Stelzner (21), Beilstein, and Chemisches Zentralblatt (Table I ) . Unless otherwise stated, the following rules apply to all three formula indexes. Corresponding entries are given for Chemical Abstracts. M e t h y l and ethyl esters of organic acids are placed under the acid, except i n Beilstein, where these esters and all other esters are found under their o w n formulas. In Stelzner and Chemisches Zentralblatt polycarboxylic polyesters w i t h methyl or ethyl ester groups are placed under the acid group after removal of these ester groups; the propyl methyl diester of malonic acid is found under C H O . A n y higher esters above ethyl are found under the formulas of the esters. Esters of orthoacids are considered as ethers of polyalcohols and are found under their own formulas: C H ( O C H ) under C H 0 . Esters of inorganic acids are found under the formula of the ester. F o r mixed esters the same rule applies as for organic acid esters. Salts of organic acids w i t h basic inorganic parts (metals, ammonia, hydrazine, etc.) are found under the acid. Salts of primary, secondary, and tertiary amines w i t h inorganic acids are found under the amines. Salts of organic bases and organic acids are found under both the base a n d 3

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Table I.

Modifications of Hill and Richter Systems Compound Indexed Under

Beilstein

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Type

Chemical Abstracts

Chem. Zentr.

Richter

Stelzner

Organic esters

Ester

Ester

Mixed organic polyesters

Ester

Ester

Inorganic esters

Ester

Ester

Ester

Ester

Ester

Salts of or­ ganic acids, amines

Parent

Parent with exception of formic, acetic, and oxalic

Parent

Parent

Parent

Salts cf or­ ganic bases and organic acids

Both parents

New formula

Both parents

Both parents

Both parents

Metal deriva­ tives of or­ ganic com­ pounds

Parents unless attached directly and only to C

New formula except for salts of or­ ganic acids

Parent unless attached directly and only to C

Parent

Parent unless attached directly and only tc C

Salts of Grignard type compounds

Hydroxide

Salt

Hydroxide

Hydroxide

Hydroxide

Salt of am­ monium oxonium, etc., com­ pounds

Hydroxide

Salt

Hydroxide

Hydroxide

Hydroxide

Methyl and ethyl under parent, all other under ester Convert M e and Et groups to acid, leave higher ester groups and use result­ ing formula

Ester

Methyl and ethyl under parent, all other under ester Convert M e and Et erroups to acid, leave higher ester groups and use result­ ing formula

Ester

the acid, Rare or unusual compounds of this type (picrates, oxalates, and aniline salts) are found under the formula of the salt, because the free base and free acid usually do not exist as such. M e t a l derivatives of organic compounds are indexed under their o w n formulas when the metal is immediately attached only to carbon. I n a l l other cases they are indexed under the formula of the parent compound. M e t a l derivatives of acetoacetic acid, malonic esters, acetylacetones, etc. (re­ active methyl group i n common), are found under the formula of the parent compound. Salts of Grignard and analogous compounds are placed under the formula of the hydroxide. Organic silicon compounds are treated i n the same manner when only one acid group is present. If more than one acid group is present, the salt is indexed under its o w n formula. Salts of ammonium, oxonium, sulfonium, etc., are placed under the formula of the corresponding hydroxide. ( C H ) I C 1 is found under C H O I . Diazon i u m compounds are handled i n the same manner, under the corresponding amine. 6

5

2

1 2

n

SEARCHING THE CHEMICAL LITERATURE Advances in Chemistry; American Chemical Society: Washington, DC, 1961.

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Definite double a n d molecular compounds of simple composition are indexed under their own formulas. Complicated compounds of this type are found under the formulas of both their components. Various criticisms (5, 8, 13, 14) of existing formula indexing systems have appeared in the literature. It is beyond the scope of this paper to discuss these at this time. F r o m the dawn of organic chemistry as such to the present time there exists a continuous record i n formula index form (Table II) of the compounds of this large branch of chemistry. Inorganic chemistry is not so fortunate. [Hoffman (12) indexed organic compounds by formula to 1909.] F r o m this date to 1920, when Chemical Abstracts began indexing by formula, there is no compilation of inorganic compounds by formula.

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Table II. ORGANIC

1828

Year Coverage on Formula Indexes 1910

1920

1930

1940

1950

RICHTER STELZNER BEILSTEIN CHEM. ABSTR. CHEM. ZENTR. BRIT ABSTR. REF ZHUR. KHIM. INORGANIC HOFFMANN CHEM. ABSTR. REF ZHUR. KHIM.

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Conclusion The above is just an indication of the use of indexes. M o r e detailed informa­ tion on this important subject is given i n the chapter o n indexes i n the " A G u i d e to the Literature of Chemistry" b y Crane, Patterson, and M a r r (10). T h e more one uses an index the more one learns about it, particularly if the index is approached receptively. T h e importance of indexing and the part it plays i n giving information can be judged b y the finding of Crane (9) that 700 words of indexing are neces­ sary for each 1000 words of abstract. Literature Cited (1) Beilsteins Handbuch der organischen Chemie, 4th ed., V o l . 29, Julius Springer, Berlin, 1939. (2) Ibid., 2nd suppl., 1956. (3) Beveridge, W . I. B., "The Art of Scientific Investigation," 2nd ed., W m . Heinemann, London, 1953. (4) British Abstracts, Abstracts A , B , and C , Index, 1948, 3-4. (5) Britton, E . C., Coleman, G . H., Perkins, R. P., Chem. Eng. News 27, 1236, 1251 (1949). (6) Chem. Abstracts 39, 5867-975 (1945). (7) Ibid., 52, lF (1958). (8) Cockburn, J. G . , Chem. Ind. (London) 1949, 837. (9) Crane, E. J., Ibid., 1956, 41. SEARCHING THE CHEMICAL LITERATURE Advances in Chemistry; American Chemical Society: Washington, DC, 1961.

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(10) Crane, E. J., Patterson, A . M., Marr, Ε . B., "Guide to the Literature of Chemistry," p. 227, Wiley, New York, 1957. (11) Hill, Ε . Α., J. Am. Chem. Soc. 22, 478-94 ( 1900). (12) Hoffman, M . K., "Lexikon der anorganischen Verbindungen," 3 vols., J. A . Barth, Leipzig, 1910-19. (13) Huntress, Ε . H., Chem. Eng. News 27, 79 (1949). (14) Laakso, P. V., Chem. & Ind. (London), 1948, 387-8. (15) Pflücke, M., Chem. Zentr., Formelregister, F I (1956). (16) Richter, M . M., "Lexikon der Kohlenstoff-Verbindungen," 3rd ed., Leopold Voss, Hamburg and Leipzig, 1910-12. (17) Serpinsky, V . V., J. Document. 12, 105 (1956). (18) Singer, T . E. R., ADVANCES IN C H E M . SER., NO. 4, 24 (1951); No. 30, 75 (1961). (19) Smith, J. F . , Ibid., No. 4, 19 (1951); No. 30, 16 (1961). (20) Spitzer, E. F., Slamecka, Vladimir, Ibid., No. 4, 30 (1951); No. 30, 136 (1961). (21) Stelzner, R., "Literatur-Register der organischen Chemie," Friedrich Vieweg & Sohn, Braunschweig, 1913-26.

Downloaded by TUFTS UNIV on June 5, 2018 | https://pubs.acs.org Publication Date: January 1, 1961 | doi: 10.1021/ba-1961-0030.ch003

BASED on paper presented before Division of Chemical Literature, Symposium on Search­ ing the Chemical Literature, 130th Meeting, A C S , Atlantic City, N . J., September 1956. Revised 1961.

SEARCHING THE CHEMICAL LITERATURE Advances in Chemistry; American Chemical Society: Washington, DC, 1961.