PHOTOGBAPHIC PKOCESSES 241 



estimate of the amount by taking it up on the point of a knife 

 or on a small spoon. 



Neither does sodium sulphite in solution keep well ; so 

 that no more of this should be dissolved than may be 

 required for use in the course of a week or two. No bromide 

 is necessary with this developer, since, given the correct 

 exposure, the results are easily controlled. Several prints may 

 be successively developed in the same solution, but it should 

 not be used after the action is evidently getting slow. When 

 the developer becomes too weak, discoloration or staining 

 may result. 



The time taken for development is usually short, but varies 

 somewhat with different makes of paper : as a rule it is com- 

 plete in from three to four minutes. With some papers, 

 although bromide is not an essential, it is still permissible to 

 use it to restrain the developing action. It should, however, 

 only be used in small quantity, since otherwise it tends to cause 

 deterioration of the black image a muddy brown-black colour 

 resulting. 



Whichever type of printing-paper has been used, it is 

 advisable for the purpose in view to glaze the print, so that 

 the surface is as flat and even as possible. This is best done by 

 allowing the print to dry after its final washing, and then to 

 soak again for about five minutes in cold water. Take a piece 

 of perfectly scratchless plate-glass, or a ferrotype plate, and 

 thoroughly clean it, avoiding hard rubbing or scratching of the 

 surface. Next rub over the surface of the plate a thin film 

 of a solution made by dissolving white wax in benzol or zylol. 

 Polish the plate, leaving just sufficient of the wax on the surface 

 to prevent adhesion of the print. Lay the wet print, face down- 

 wards, on the plate and well rub it on the back with clean 

 blotting-paper to ensure that no water remains between it and 

 the print. To do this most effectually an india-rubber roller- 

 squeegee may be used. Place the whole on edge to dry, and if 

 the process has been properly carried out, the print will when 

 thoroughly dry leave the plate of its own accord, or it may be 

 loosened at one corner and then drawn off. The result should 

 be a highly glazed surface, which usually adds considerably to its 

 brilliancy as a print. A still more highly glazed surface may be 

 obtained by coating the print with a thin layer of collodion. 



