Kapustinskii's empirical equations have been used to calculate the lattice energies of the chalcogenides, M,Ch, MCh, and M,Ch,, of the metals from scandium to zinc. These have been used in Born-Haber calculations of the enthalpies of formation. Enthalpies of various disproportionation and reduction reactions of the chalcogenides have also been calculated, and the results are discussed.USING the lattice energies of the neighbouring stable compounds in the Periodic Table and, for some compounds, figures calculated from the Born-Lande equation, Grimm and Herzfield calculated by the Born-Haber cycle the enthalpies of formation of a number of hypothetical compounds. However, the Born-Lande and certain other equations employed for the calculation of lattice energies depend on an exact knowledge of the crystal structures of the compounds. This restriction is not inherent in the equation devised by Kapustinskii : where U is the lattice energy, n the total number of ions in the molecule, and Z,, 2-, and Y,, rthe ionic charges and radii, respectively, of the species involved. Although this equation is subject to a number of criticisms and gives lattice energies that are generally on the low side, it has led to the theoretical prediction and subsequent synthesis of a number of hitherto unknown C O M P O U~~S .~,~ A simpler equation proposed by Kapustinskii : U = 256.1nZ+Z-/(~,. + Y -) kcal. molep1 (B)and giving somewhat higher lattice energies, has recently been invoked to provide lattice energies for the Born-Haber calculation of the enthalpies of formation of the solid mono-, di-, and tri-halides of the elements of the first transition series (scandium to zinc).6 In view of the present considerable interest in the lubricating and electrical properties of the chalcogenides of these elements, this treatment has been extended to include the oxides, sulphides, selenides, and tellurides. CALCULATIONS AND RESULTSBoth equations (A) and (B) have been used to calculate lattice energies of the chalcogenides M,Ch, MCh, and M,Ch,, from scandium to zinc. The enthalpies of formation (AH,) were then obtained from Born-Haber equations, with adjustments for ionisation potentials, electron affinity, and enthalpies of sublimation and dissociation appropriate to the type of compound.

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The following are summaries of seven of the papers presented at the Research and Development Topics in Analytical Chemistry meeting of the Analytical Division held on May 4th and 5th, 1976, at the University of Exeter.

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The following are summaries of papers presented at the Joint Meeting of the Thin-Layer Chromatography Group and the Department of Textile Industries of the University of Leeds held from January 5th to 7th, 1966, and reported in the March issue of Proceedings (p. 39).