(SCIENTISTS.) MARIE CURIE. Typed Document Signed, "M. Curie," as Laboratory Director, certifying a sample of mesothorium [isotope of radium] contained in a glass tube and emitting radiation equivalent to 5.22 milligrams of radium, in French. Accomplished in secretarial hand. 1 page, tall 4to, "Laboratoire Curie" stationery; marked fading to typed text (but still legible; signature and accomplished text bold), folds, remnants of hinging at upper edge verso. Paris, 9 June 1923
