Indexes of Data for Identification Purposes

Abstract

FOR, the purpose of identifying crystalline solids three indexes have been initiated. (1) The Barker index of morphological data (derived from measurements of interfacial angles on single crystals) was outlined in his book "Systematic Crystallography" (1930) and reviewed by Spiller and Porter¹ in 1939. It will include all crystals (other than cubic, to which the method is not applicable) in Groth's "Chemische Krystallographie", which was completed in 1918. These number some 7,300. To these may be added the (probably small) number of compounds studied goniometrically since 1918. (2) Data on the refractive indexes of upwards of a thousand substances have been collected by Winchell in "The Optical Properties of Organic Compounds"². (3) The index of X-ray diffraction data^3,4 sponsored by the American Society for Testing Materials and the Institute of Physics covers some 2,500 substances, including those in the supplement now in preparation.