Abstract
An advance in the technique of using the Jamin interferometer for the determination of the dispersion of gases has been effected by making a systematic allowance for fringe-drift by means of photographic measurements. New values of the refraction and dispersion of sulphur dioxide and sulphuretted hydrogen have been determined, reduced to ‘infinite dilution’ by means of newly measured pressure coefficients, in order to allow for departure from the gas laws. The refraction and dispersion of carbon oxysulphide have been measured for the first time.