difficulties make necessary a resident staff member's reviewing the coder's and checker's work, this 

 "arbitrator's" initials are also entered here ("Arbitrated by"). 



As the illustration of the Code Sheet indicates, this side of the Code Sheet on which the actual 

 coding is entered is considered to be the "inside" of the Sheet. When folded for mailing or filing, 

 then, this coding is on the inner surface and the reverse side (the outer surface) forms a "front" and 

 "back" of the Code Sheet. 



The front side (Figure 6) is generally self explanatory of entries to be made identifying the 

 chemical tested, the information source, and the Code Sheet Number. In the space in which coders 

 are instructed not to make an entry, only the CBCC resident chemists enter the name of the chemical 

 tested, using, for consistency, the name by which the chemical has been filed in the CBCC Chemistry 

 Files, generally conforming to Chemical Abstracts nomenclature. 



The back side of the folded Code Sheet (Figure 4) is also generally self explanatory, being for 

 the coders' recording of properties of the test compound, whenever such information is given by the 

 information source. 



All completed Code Sheets, after being assigned Code Sheet Numbers, checked, arbitrated, and 

 processed by the chemists and IBM punch operators, are filed in a Code Sheet File which serves as a 

 master file of the information collected by the CBCC. This file is described later. 



III. RECORDING OF INFORMATION ABOUT CHEMICALS 

 AND CODING OF CHEMICAL STRUCTURES 



Space does not permit more than an outline of the procedures the Center used for handling 

 information about chemicals used in chemical-biological tests. The Chemistry Code was published 

 in 1950. By this Code, the CBCC recorded on IBM punched cards the structures of compounds tested 

 for their biological effects. The actual process of coding the chemical information paralleled that of 

 coding biological data. For each compound, every effort was made to determine its molecular structure, 

 all its properties, and the name by which it is indexed in the most universally used reference to current 

 chemical literature, Chemical Abstracts. In addition, the chemists recorded all information given 

 about alternate chemical names, proprietary names, common names, commercial sources, and natural 

 sources. Also, a reference was recorded to the literature article or other source of chemical-biological 

 information in which the chemical was first encountered by the CBCC. 



Each identified chemical was assigned a reference number at the time of recording the infor- 

 mation about it. The reference number must be understood to be distinct from the coding of chemicals' 

 specific structures; the number represents essentially only the sequence in which the chemical was 

 recorded and coded by the CBCC. The numbers are referred to as the CBCC Chemical Serial Numbers 

 (abbreviated to "CBC Numbers"). This Serial Number is basically of six units; an additional two units 

 can be appended (separated by a dash from the sixth unit) to the basic Serial Number to indicate the 

 compound's various salts, solvates, and isotopes used in biological tests. 



All information about a single compound was written on a special sheet, the Chemistry Code 

 Sheet, including the compound's Serial Number and its structure, both as a structural formula diagram 

 and as a coded molecular formula. The Chemistry Code Sheet, front and back, is illustrated by 

 Figures 7 and 8. 



The coded structure of each compound and its Serial Number were punched on IBM cards 

 (occasionally, two IBM cards were needed for a compound of especially large molecular structure). 

 The specially printed IBM card used for punching chemical structures is illustrated in Figure 3. The 

 files of chemistry IBM punched cards and of the Chemistry Code Sheets are described later. 



A Method for Coding Chemicals for Correlation and Classification (1950): $1. 50. 

 National Research Council, Washington, D. C. 



200 - 



