Punched-Card System for Tabulation of Crystallographic Data W. C. McCRONEl Armour Research Foundation
of Illinois Institute of Technology, Chicago 16, 111.
Tables, and similar sources list such common properties as densities, refractive indices, and solubilities. It is important t o complete these tabulations and to extend the tables to cover additional properties useful to the analyst. Unfortunately, the use of crystallographic data for the characterization and identification of substances, especially organic compounds, has not become general. One reason for this is the lack of sufficient data for the common and important substances encountered by the analyst. I n March 1948, therefore, the Crystallography GI oup a t the Armour Research Foundation began the determination, checking, and publication ( 2 ) of crystallographic data as a monthly column in .~SALYTICAL CHEMISTRY.Since that time more than 100 complete descriptions have been published. I n addition, more than 20 crystallographers both a t , and away from, the foundation have published a t least one description in the Crystallographic Data series in r\\ ~ L Y T I C A L CHEMISTRY.
The use of crystallographic data for characterization and identification of substances, especially organic compounds, has developed slowly, partly because of the lack of adequate reference data and of analytically useful tables of available data. A punched-card system is, therefore, proposed as a means of collecting and using crptallographic data. The card contains all of the data normally published in the Crystallographic Data series in ANALYTICALCHEMISTRY: morphological, x-ray, optical, and fusion properties. Enough data are punched on the cards so that all of the quantitative crystallographic properties (crystal system, axial ratios, interaxial angles, unit cell dimensions, density, refractive indices, optic axial angle, and extinction angle) niay be read directly or calculated from punched data.
T
HE identification of an unknown substance is always based on the determination of one or more physical or chemical properties. The analyst must, therefore, have access to tabulations of physical and chemical properties in order t o complete his identification of an unknoivn substance. The best properties t o use are those which are easily measured x i t h high accuracy, are not seriously affected by impurities, and have been measured for most common and important substances. An important adjunct in any analytical laboratory is a tabulation of accurate physical data for all substances the analyst is likely t o encounter. The handbooks, International Critical 1
DEVELOPMERT O F PCSCHED-C4RD SYSTEM
As a part of this over-all piogram it became necessary to be able to find quickly any previously published data for any given substance. It seemed desirable to arrange these data in a form that would be useful analytically. -4punched-card system was chosen, because it seemed possible by this means to tabulate all of the useful data and t o make them available either by name of the substance or by property. .4 number of cards a-eie studied and used, including one published by Kirkpatrick ( 1 ) (Figure 4), until finally the card shown in Figures 1, 2, and 3 was developed. Since that time more than 4000 cards have been completed,
Present address, 3140 South Nichigan A v e . , C h i c a g o 16, Ill.
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