Paper samples provided with color layers containing various copper acetates were exposed to visible light with wavelengths above 340 nm (123,6 footcandles). Seventy-five hours of irradiation were sufficient to give rise to distinct physicochemical changes of the components as observed by infrared spectrometry. Treatment of the samples with gaseous sulfur-dioxide caused the degradation of the copper pigments as well as the simultaneous autoxidation of cellulose catalyzed by the copper ions present. On the basis of infrared spectra there is strong evidence for the formation of reddish-brown globules of Chevreul's salt, Cu₂SO₃.CuSO₃.2H₂O, as a consequence of sulfur-dioxide treatment. These findings are confirmed by x-ray diffraction techniques, indicating the presence of metallic copper produced by the reductive action of sulfur-dioxide. Similar globules were already found on decayed paper samples of original objects of illuminated graphic art. See also 19-1244. -- AATA