The formula for the optical rotatory dispersion of quartz

The optical rotation of quartz has been measured over a large band of wavelengths. We have Gumlich’s original work over the range from λ = 2·140 μ to λ = 0·21935 μ , repeated and extended into the ultra-violet by Soret and Sarasin and Guye. More recently a series of accurate measurements covering the same range was published by Lowry, and then Duclaux and Jeantet gave a series of results for a range in the ultra-violet from λ = 0·30876 μ to λ = 0·1853980 μ . Finally, Lowry and Coode-Adams, having improved the accuracy of their original method, succeeded in obtaining a very accurate set of readings extending from λ = 2·5170 μ in the infra-red to λ = 0·2280 μ in the ultra-violet, reaching thus just up to the region measured by Duclaux and Jeantet. Various attempts have been made to fit these results into a formula. Gumlich found it possible to represent his results by a formula of the type ω = α 1 /λ 2 + α 2 /λ 4 + α 3 /λ 6 + α 4 /λ 8 + α 5 /λ 10 , but Kettler had almost equal success with the simpler form ω = (λ 2 α)/β.