XEE4140975 Ultraviolet rays: effects. We cover the ears of a rabbit with black cardboard or cut the letters R and V, then we expose the animal to the ultra violet rays of a mercury lamp: the ears show traces of burning identical to those of a sunburn. Anonymous illustration from 1925. Private collection. by Anonymous; Private Collection; (add.info.: Ultraviolet rays: effects. We cover the ears of a rabbit with black cardboard or cut the letters R and V, then we expose the animal to the ultra violet rays of a mercury lamp: the ears show traces of burning identical to those of a sunburn. Anonymous illustration from 1925. Private collection.); Stefano Bianchetti; out of copyright.