e d k d by
Rod O'Connor Texas A&M Universitv College Station. TX 7784j
The Case of the Isotopic Artist
T o check vour answer. see "Chemistrv in Art: Radiochem- ~ istry and Forgery", by F E. Rogers in tke June 1972 issue of the JOURNAL OF CHEMICAL EDUCATION (DO.418~
Rod O'Connor Texas A & M University College Station, T X 77843
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To obtain detailed solutions or to submit problems for "Brain Han Van Meegeran (1889-1947) is considered by many to Tinglers", write to Dr. Rod O'Connor, Department of Chemistry, have heen the master of art forgery, having amassed an estiTexas A&M University, College Station, TX 77843 mated $3,000,000 from his "art." Perhaps his most famous work was Christ and His Disciples a t Emmaus, "discovered" as an "original Vermeer" (1632-75) in 1937 and sold for This problem was taken from O'Connor, Rod, "Fundamentals of $280,000. In 1945 Van Meegeran confessed to the forgery of Chemistry", 2nd edition, Harper & Row Publ., New York, 1977. six "Vermeers," including the Emmaus, but art experts examined the paintings and declared them to be true "origiSucessive Decay of Ra-226 nals." The only support to Van Meegeran's confession came %Rn + :He '%a ty, = 1600 yr from a Belgian chemist, Paul Coremans, hut it was not until 1968 that the Emmaus was proved a forgery with radiochemical evidence obtained by Bernard Keisch of the Mellon 2A:po Er22At -% Institute. The evidence hinged on two nuclear transformations in'::Pb + :He volving lead in white pigments ty, = 3.0 mi" used by both Vermeer and Van Meegeran in their paintings. The lead used in making the pigments contained some of the isotope $iOPb, which undergoes P-decay with a half-life of 22 years, followed by successive decay steps (shown a t far right) rapidly leading to stable lead-206. Also present, as an impurity in the lead used, was a trace of radium-226, which very slowly decays by a series of steps (right) to lead-210. The difference between the ;ioPh@Ra ratios in the white pigments in "real" and "forged" Vemeers was the vital clue to proving- the Emmaus a forgery. What kind of difference must have been found?
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Volume 57, Number 4, April 1980 1 271
