Optic moments of organic molecules in relation to crystalline and magnetic birefringence

Summary

The results of observations made on the magnetic birefringence of organic solids dissolved in liquid carbon tetrachloride are given. The observed values of C_M for naphthalene solutions are compared with the value of C_M observed by Salceanu on molten naphthalene and found to be in good agreement. The principal optic axes of the diphenyl crystal are fixed on the basis of the author’s own observations, those of Groth and also of Hendricks and Jefferson. The direction of maximum refractive index has been found to coincide with the direction which has been assigned to that of the length of the molecule by Krishnan from his diamagnetic observations on the crystal. The optic moments of diphenyl molecule are calculated from the refractive indices and are found to satisfy the observed magnetic birefringence and the refractive index of the solution. The optic moments of the dibenzyl molecule are similarly calculated from the refractive indices and found to agree with the observed refractive index of the liquid dibenzyl.