Abstract
Measurements of the spontaneous birefringence of the ferroelectric phase (4K to TC(f. e.) = 466K), of its dispersion in the visible (300K) and of the spontaneous Faraday rotation in the ferromagnetic phase (4K to TC(f. m.) =16K) are reported. The rotation amounts to 3450 deg. cm-1 at 4K and Λ = 643nm along an optic axis.