7) It appears from previous measurements that this orientational axis is identical with the longitudinal axis of inertia, however, we have not proved this generalization rigorously.(8) We are indebted to the referees for their comments on this matter. (9) Similar relations were derived by Norden [Chem. Script., 1, 145 (1971)] for the interpretation of the linear dichroic spectra of certain triarylmethane dyes. (10) The "in-plane" transitions are those polarized in the best plane of the molecule (which includes the twofold symmetry axis) whereasthe "out-of-plane" transitions are those polarized out of this plane.

The normal-incidence spectral reflectance of aqueous solutions of alkali halides has been measured in the spectral range 350-5000 cm™1. From the measured values of reflectance we have used Kramers-Kronig phase-shift analysis to provide values of the real and imaginary parts of the complex refractive indices Ñ = n + ik of the solutions. The plots of k(v) vs. v give quantitative measures of absorption band intensities as well as positions; we find that the negative ions produce greater changes in the absorption spectrum of the solvent than do the positive ions. Similarly, we find that the negative ions have greater influence on n(v) in the near infrared; all the halide ions increase n(y) to values above that of water but, at a common concentration, the iodide ion has the greatest effect. The primary influence of the ions on n(v) in the near infrared can be attributed to electronic bands in the ultraviolet. The influence of the ions on the characteristic water bands is related to the influence of the ions on the intermolecular structure of water. Publication costs assisted by Environment CanadaThe laser Raman spectra of aqueous MgS04 solutions have been recorded at pressures up to 1 kbar for temperatures between 7.0 and 25.0°. The results are used to calculate the volume changes of dissociation of MgS04°c ontact ion pairs (average V = -20.3 ± 1.4 cm3 mol'1 between 7.0 and 25.0°). The absence of temperature dependence of AV and the different values of V obtained by other techniques are discussed in terms of a multistate ion pair equilibrium process.