Faraday Effect in Gases and Vapors III*

Verdet constants over the spectral range 3635 A to 9875 A have now been measured for 11 gases and vapors (also Pyrex glass) in addition to the 22 previously reported. The list includes nitric oxide gas, ammonia, and sulfur dioxide; also the vapors of water, deuterium oxide, ethyl and methyl alcohols, ether, chloroform, carbon tetrachloride, and carbon disulfide. Nitric oxide shows a negative rotation and a larger Verdet constant and Faraday dispersion than any other of the (gaseous) materials tested except carbon disulfide vapor.For comparison purposes the Verdet constants of the latter eight substances on the list have been measured for the liquid state over the same spectral range. The ratio of Verdet constants for water in the liquid and vapor states is 2 to 5 times larger than for any other material tested. Deuterium oxide in vapor or liquid states shows about the same Verdet ratio to water, viz 0.97, as deuterium and hydrogen gases. Faraday temperature coefficients have also been determined. For constant volume conditions these are very small save for nitric oxide gas. A theoretical explanation of the rotation of nitric oxide is attempted.