On the refractive indices of gaseous nitric oxide, sulphur dioxide, and sulphur trioxide

Abstract

Dufet only records two determinations of the index of nitric oxide: that of Dulong, who found 1.000302 for white light, and that of Mascart, who gives, for sodium light, 1.0002975, taking air as 1.0002928. The latter states that the gas he used contained about 10 per cent, of gas not absorbable by ferrous sulphate, for which allowance was made; but the analysis was not very accurate. As the index is abnormally high, and methods of purifying gases have improved since 1877, it seemed desirable to repeat the determination.