Refractive indices and dispersions of gases and vapours

Abstract

1. Refractive indices and dispersions have been measured for 16 gases and vapours using a Zeiss Interferometer of the Rayleigh type. Five wave-lengths 6440, 5462, 5087, 4801 and 4360 have been employed for the purpose. 2. Accurate values of compressibilities for the gases and approximate values for the vapours have been obtained by studying the variation of refractive index with pressure. 3. The electronic polarisation obtained in this paper have been compared with the dielectric polarisations given in the earlier paper1 and from the two the atomic polarisations have been calculated. 4. The values of refractive index for the gases and vapours by the author have been compared with existing data by others and discussed. 5. Refractivities in the liquid state for substances which are liquids at the ordinary temperature and pressure were measured for two wavelengths using a Pulfrich Refractometer and a mercury arc. These values have been compared with those obtained for the corresponding vapours. 6. The results show that in general the refractivities of the vapours are slightly higher than those of the liquids. 7. The dispersions in the liquid and vapour states have been compared. The indications are that the values in the vapours are slightly higher than in the corresponding liquids.