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Expressions for the electron affinities of halogen atoms have been obtained by consideration of five different forms of interaction potential. These expressions have been used to calculate electron affinities for F, CI, Br, and I atoms from molecular constants for 20 alkali-metal halides. In view of the approximations involved, the results agree well with the only reliable experimental values available, and also with values obtained from lattice energy measurements. The relative effects of the various potential functions upon the results are discussed.

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Earlier ESR studies on biological materials (So g o et al., 1956) have revealed that various constituents of plants show free radicaI content in them. Since the study of this kind of material a great deal of work has been done in this field (In g r a m , 1958). In the present paper the ESR study of 1,3,5-trihydroxy-2,7-dimethyl-anthraquinone-8-0-aD -glucopyranoside named as nodososide has been undertaken. The studies made here have revealed that the compound mentioned above is a free radical. The measurements of line shape, line width and g value were carried out. The Kubo and Tomita theory of ESR line width has been utilized to estimate the exchange frequency as well as asymptotic Curie temperature of the compound. The static magnetic susceptibility of the compound has been measured and the percentage radical concentration of the compound has been obtained. On the basis of these measurements a suitable stable intermediate structure of nodososide has been proposed. Experimental After a chemical investigation (R i z v i et al. 1971) of Cassia nodosa flower, very useful for medicinal purposes (C h o p r a et al. 1956 and K i r t i k e r e t al. 1933), a brown compound anthraquinone glycoside named as nodososide