Studies in Refractive Index I and II

Abstract

In Part I four methods are described for measuring the refractive index of strongly absorbing liquids. The first two of these depend upon determination of the critical angle of reflection of monochromatic light at a glass-liquid interface. In the third, white light was reflected at angles near the critical angle and was then allowed to enter a spectrograph. Microdensitometer records were made of the resulting spectrograms. Peaks in the record correspond to maxima of the refractive index. In the fourth method the transmitted light was examined visually in a spectroscope. In Part II these methods have been applied to a saturated aqueous solution of potassium permanganate. As a result a dispersion curve was found with a strong anomaly centering about 5473A and in addition a series of minor anomalies corresponding to the banded structure of the absorption spectrum. It is concluded that the band at 5473A is that caused by the fundamental frequency of an electronic transition in the manganese atom.