The determination of the precise nature of photographs is sometimes difficult or even impossible to do by simple visual examination. Complementary tests were applied to the study of E. Atget's prints in the Ville de Paris collections. Cross sections permitted a stratigraphic study in which the different nature of the three printing processes showed clearly: 2 without emulsion, 1 with emulsion. Applied chemical analysis allowed identification of albumin, starch, or gelatin in the layers. The brown tones of the samples (taken from the margins) or the presence of encaustic on the surface sometimes hampered this analysis by coloring. Microfluorescence x-ray spectrometry was used to analyze the metal elements. By confirming the nature of the toning and of the light-sensitive salts, it was determined that the prints under study, even though they differ sensibly in color, were all gold toned. Lastly microchemical test analyses of fibers were carried out on various types of old photographic pages before being applied to some thirty Atget prints dated 1890 to 1973. This period is particularly important in the evolution of supports.