A Manual Of Photography

CHAPTER I. SELECTION OF PAPER FOR PHOTOGRAPHIC PURPOSES. It is natural to suppose, that a process which involves the most delicate chemical changes requires more than ordinary care in the selection of the substance upon which preparations of a photographic character are to be spread. This becomes the more evident as we proceed in our experiments to produce im- proved states of sensitiveness. As the material, whatever it may be, is rendered more susceptible of solar influence, the greater is the difficulty of producing perfectly uniform surfaces, and with paper this is more particularly experienced than withmetal or glass plates. Paper is, however, so convenient and so economical, that it is of the first importance to overcome the difficulties which stand in the way of its use, as the tablet on which the photographic picture is to be delineated. The principal difficulty we have to contend with in using paper, is the different rates of imbibition which we often meet with in different parts of the same sheet, arising from trifling inequalities in its texture and unequal sizing. 1his is, to a certain extent, to be overcome by a very caretul examination of each sheet by