General and physical chemistry

1911 Journal of the Chemical Society Abstracts  
the author obtains for the dielectric constant of a mixture consisting of one substance imbedded in another a generalised Lorenz-Lorentz expression which involves a " form-number " u. This number is determined by the shape of the imbedded particles, and is greater than 2 when the particles are not spherical. The values of u in different cases are discussed ; it is shown also how they may be derived from optical data. The results obtained for diff ereiit substances correspond in general with
more » ... in general with their relative molecular complexities. The advance with respect to previous empirical improvement 8 of the Lorenz-Lorentz formula consists in the mode of deduction and the theoretical interpretation of the quantity u, connexion with a study of the refractive indices of salt solutions and the refractive constants of dissolved salts (following abstract), a knowledge of the exact value of the index of refraction of water at 25' was required. Determinations of the constant have, therefore, been made a t this temperature, and also at 20' and 30°, special attention being devoted to the purity of the water and the careful regulation of the temperature. The values obtained for [n], are 1.33299 a t 20°, 1,33248 at 2 5 O , and 1.33190 at 30°, when referred to air at the same temperatures, and 1.33335 at Z O O , 1.33284 a t 25' , and 1.33225 at 30°, when referred $0 vacuum. These values are probably correct within 0.00002. . Chem. Xoc., 1911, 33, 901--922).--Much work has already been done on the refractive indices of solutions of electrolytes, but the accuracy of most of the results is regarded as doubtful, insufficient care having been taken, in many cases, to ensure the freedom of the substances from probable impurities, especially moisture. The densities and refractive indices of solutions of the chlorides, bromides, and iodides of lithium, sodium, and potassium have been determined at 25' at various concentrations. The increase i n density of the solutions with increasing concentration is nearly, but not quite, proportional to the quantity of salt in unit volume. The values obtained by dividing the differences between the densities of the solutions and of water by the molal concentrations have been calculated. These increments decrease slowly with increasing concentration, except in the case of lithium iodide. This
doi:10.1039/ca9110005557 fatcat:mxrh6pwjzzgbfeagiwqugf73jq