3160a.     ---------------.  [SELWOOD, P. W.]  Magnetism and the Structure of Catalytically Active Solids.  Advances in Catalysis.  Academic Press, Inc., New York, vol. 3, 1951, pp. 27-106.

        Status of magnetic studies on catalyst structure is given.  The following conclusions are drawn:  The magnetic methods often give evidence for the oxidation state of catalytically active solids which contain elements of the transition series.  This is especially true for V, Cr, Mn, Fe, Co, Ni, and Cu.  Sometimes the magnetic method reveals the existence of valence bonds between adjacent positive ions, such as between Fe and Fe in hydrous or supported Fe sesquioxide.  Almost always the magnetic method gives some information concerning the atomic environment of positive ions in hydrous or supported oxides.  This information is related to the number of positive ions surrounding a given positive ion, for example, to the number of nearest Fe neighbors to a given Fe ion in Fe sesquioxide.  The magnetic method, together with other methods, has revealed that the oxidation state of a supported oxide may, under certain circumstances, be influenced by the crystal structure of the support.  In some cases there has been established a definite relation between the information obtainable from magnetic measurements and the actual catalytic activity.  The methods described are not yet applicable to diamagnetic substances such as alumina or silica, but have definite applications to some systems in which these substances are used as supports.  The thermomagnetic method of analysis is a tool of major use in detecting and estimating certain components in catalysts.  These components are the ferromagnetic substances Fe, Co, Ni, Fe₃O₄, γ-Fe₂O₃, Fe₃C, and Fe₃C.  In certain cases of a ferromagnetic metal supported or alloyed with a nonferromagnetic metal the thermomagnetic method can reveal alloy structure in a manner inaccessible by other tools.  62 refs. given.

        ----------.  See abs. 2327, 3500.

        SEMILLER, H.  See abs. 3073.

        SEN, R.  See abs. 467.

        SEN, S.  See abs. 1186.

        SENDERSENS, J. B.  See abs. 3001, 3002, 3003, 3004,     3005.

        SENGLET, R.  See abs. 356.

        SENOO, H.  See abs. 2502, 2503.

        SEON, M.  See abs. 2194.