Abstract
Absolute values for the Kerr constant in anhydrous ammonia, nitrogen and oxygen have been determind. Measurements in NH3 were made at wavelengths of 6500A and 5750A, pressures from 13 to 30 atmospheres, and temperatures from 40° to 80°C. In N2 and O2 the wavelength used was 6500A, pressures in the neighborhood of 100 atmospheres and temperatures from 20° to 65°C. The absolute value for the Kerr constant reduced to N. P. T. and 6500A is for NH3 (62.3±1.8)1012, for N2 (4.64±0.10)1012 and O2 (6.94±0.30)1012.