On the refraction and dispersion of carbon dioxide, carbon monoxide, and methane

Source abstract

Abstract In continuation of previous work on the refraction and dispersion of gaseous elements and compounds within the limits of the visible spectrum, the refractivities of the gases named above were measured by the authors in 1914. Publication of results has been delayed by the war. Carbon Dioxide. The gas was prepared by heating a mixture of three parts of bichromate of potash and one part of sodium carbonate in vacuo and drying with phosphorus pentoxide. It was then condensed several times in liquid air and impurities pumped off. But, notwithstanding these precautions, tests by absorption in potassium hydroxide always indicated the presence of a small quantity (about 0.1 per cent.) of unabsorbed gas, which was assumed to be air and was allowed for in calculating the refractive index.