Fig. 2From: Preliminary photographs and improved positives: discovering the New York Public Library’s Arctic Exploration albumXRF spectra acquired from dark gray areas of a plate 93 and b plate 97 (preliminary photographs), expected to yield a more intense Ag signal. Both spectra show a very weak peak at energies corresponding to the Ag Lβ2 line, as well as Au peaks indicating that these photographs were gold-toned. Exact locations of the spots examined are marked with red dotsBack to article page