The history, theory and practice of autoradiography are summarized. Examples are discussed: 15th century manuscript illuminations which were added to by the 19th century Spanish Forger, and paintings by American painter Ralph Albert Blakelock (1847-1919) and his daughter Marian Blakelock. Pigments identified from the manuscript included gold, copper-bearing blue, sodium-bearing blue (possibly ultramarine), mercury-bearing red, and a copper and arsenic-bearing green. (Abstractor's note: suggestion that this is copper arsenite. Scheele's Green, first made in 1878; or copper aceto-arsenite, Emerald Green, first made in 1814.) Pigments on the Blakelock paintings were: a lead-bearing white ground, a manganesebearing layer over the white ground, arsenic-bearing pigments, a mercury-bearing red (probably vermilion), and a zinc and barium-bearing ground. See also AATA 15-1446.