ABSTRACT
A piece of glass is immersed in benzene contained in a cell. The glass piece will be rendered invisible when, in accordance with, the refractive index of the mixture is equal to that of the glass. If white light is used for illumination, the edges of the glass piece reveal their presence by iridescence. The light reflected from the surface of a cyanine crystal, fused in contact with glass, is examined by a direct-vision prism. The reflectivity of a vitreous surface increases considerably as the incidence varies from normal to grazing. The light may propagate in transparent solid cylinders if it enters at an incidence suitable for total internal reflections.
