ThE action of photographic reducers upon the silver deposits in photographic plates and films has been studied rather extensively by various workers in the field of photographic research. These investigations have been carried out both from the practical and theoretical point of view. Among the most prominent researches of this nature may be mentioned those by Luppo-CramerJ A. and L. Lumiere and Seyewetz, 2 Stenger and Heller, a Deck, 4 Nietz and Huse, 5 and Sheppardfi Practically all of this work has dealt with the reduction of density in the case of photographic materials coated on transparent supports, such as plates and films, for not until a satisfactory method for paper sensitometry ; was available could the usual /q. and D. methods be applied to the study of the reduction of density in photographic printing-out papers.
Since it is evident that the quality of the photographic print may in some cases be improved by the proper reduction of density, it seemed advisable to investigate the effect of various reducers when used for this purpose. The problem is considered in this paper entirely from the sensitometric standpoint, very little attention being paid to the theory of the action of these reducers oi1 the deposits, and all conclusions relative to the merit of the various reducers tried are based upon the consideration of the sensitometric curves rather than upon actual prints. The sensitometric method for the study of the characteristics of photographic ma-* Communicated by Dr. C. E. K. Mees, Director. fronl the Research Laboratory of the Eastman Kodak Company.