GCI senior scientist Dusan Stulik performing X-ray fluorescence (XRF) analysis of an album of photographs attributed to French photographer Eugène Durieu. In using XRF and Fourier transform infrared spectrometry (FTIR) to analyze the photographs, GCI scientists discovered that Durieu experimented with different toning procedures, including platinum. A number of photos in the album may be the oldest extant examples of platinum and combination toning. Photo: Herant Khanjian.