The dispersion phenomena of some monoclinic Felspars

Abstract

In the present paper the dispersion of the refractive indices of monoelinie felspars from four different localities is given, likewise that of the optic axial angle and of the optic axes in some of them. The method of investigation and instruments for these studies have been already mentioned in my previous paper. As the refractive indices and dispersion of the glass hemisphere of the total-reflectometer have not so far been given, I shall in the first place state the way in which they have been determined and their values and the degree of accuracy attainable, for the dispersion of the glass hemisphere differs to au appreciable degree from that of other instruments of the same kind.