Action of Magnetic Fields on the Refractive Index of Carbon Dioxide Gas

Abstract

IN NATURE of Nov. 20, 1926, p. 734, Messrs. Ghosh and Mahanti report an alteration of refractive index of carbon dioxide on applying a magnetic field of 3600 gauss transversely to the direction of propagation of the light. They attempt to explain this effect by an orientation of the molecules in the magnetic field. Now in a gas the molecules of which are orientated, if any effect on the refractive index were expected, one would naturally anticipate the primary effect would be a double refraction. Krishnan (Proceedings of the Indian Association for the Cultivation of Science, 10, 1. 35; 1926) has searched diligently for this effect in pure carbon dioxide over the whole range of pressures used by Ghosh and Mahanti, and his results were uniformly negative. For this reason an effect of the type described could not be due to molecular orientation. Further, the basis for the supposition of orientation in polyatomic gases, namely, the experiments of Glaser on their susceptibility, has been rendered very uncertain by Lehrer (Ann. d. Physik, 81, 229; 1926). Using a more satisfactory method, the latter was unable to reproduce Glaser's results. These facts made the experiments of Ghosh and Mahanti very difficult to understand, and it was considered worth while to repeat them.