The dielectric coefficients of gases.—Part II. The lower hydrides of carbon and silicon, oxygen, nitrogen, oxides of nitrogen and carbon, and fluorides of silicon and sulphur

Abstract
In Part I measurements of the dielectric coefficients of hydrogen and the rare gases at two temperatures were recorded. The investigation has now been extended to a number of other gases with a view to determining the electric moment of their molecules and comparing the values of the dielectric coefficient with those of the refractive index at long wave-lengths. The results now given are those of a series of measurements dating from 1928, and during their progress several papers comprising the same subject have been published. These will be discussed later and the results compared. When dealing with all but the simplest gasses a knowledge of the compressibility is essential in order to reduce the values of the dielectric coefficient at different temperatures to those for equal density; it is also desirable to employ gases which have been purified with the greatest care. The compressibilities of the gases under reference have been determined approximately by measuring the dielectric coefficient at different pressure as for ammonia and several values have been confirmed by direct determination or by refractometric measurements, an account of which will be given elsewhere.