On the theory of optical activity I—General theory of a system of coupled isotropic oscillators II—Molecules with a binary axis of symmetry

The problem of correlating optical activity with other optical and chemical properties of a substance has been treated in recent times by several authors, using rather different methods. Kuhn starts from the general theory, given by the author of this paper, and simplifies it in such a way that he gets practical formulæ. Gray, de Mallemann and Boys develop a theory of their own. Boys finds a rather simple expres­sion for the rotatory power, which contains nothing else but the refractivities and the effective radii of the chemical groups involved. There is no question about the general theory. It is, in fact, a problem of quantum optics and has been treated from this standpoint.¶ The chief result is that the rotation effect is due to the same set of virtual oscillators which determine the dispersion. Therefore it is possible to replace the quantum mechanical system by a classical one, consisting of a set of harmonic resonators coupled by electric and magnetic forces.