The temperature variation of the rotatory power of quartz from 30° to 410°

Abstract

The temperature variation of the rotatory power of quartz has been measured from 30° to 410°C. for a range of wavelengths extending from 6000Å to 2500Å. It is found that the temperature (1/ρ0 Δρ/Δt) exhibits an increase in the ultraviolet. The rotatory dispersion of quartz is accurately expressible from the visible to the extreme ultraviolet by a formula of the form, ρ= α ν ²/( ν₀ ²- ν ²)² where ν = 1/ λ Taking 'a' to be invariable with temperature (for which reasons have been put forward) but v₀ to vary with it, the thermal variation of the rotatory power has been calculated over the whole range of wavelengths for the different temperatures. The theoretical calculation agrees very well with the observational data, the rate of shift of v₀ being found to be roughly the same as that estimated from the thermal variation of the refraction. It is shown that theoretically we should expect the temperature coefficient to increase with decrease of wavelength, a fact which is confirmed by experiment.