An Instrument for the Measurement of the Index of Refraction of Liquids in the Wave-Length Range 200 m μ to 1000 m μ

An instrument which can be used from 200 mμ to 1000 mμ with transparent liquids for the determination of the refractive index, relative to air with an error of ±.0002 is described. A cell consisting of two quartz plates and an air space is rotated in the liquid through which is passing a parallel monochromatic beam of light, and the critical angle at the quartz air interface is determined. The instrument in its present form is particularly adapted for use with a Beckman Model DU quartz spectrophotometer. Results for water and n-hexane are given as examples.