CHAPTER X 



PHOTOGRAPHIC PROCESSES 



Negative Development. The method of developing photo- 

 micrographic negatives does not differ from that adopted 

 in ordinary photography, and the reader is recommended to 

 refer to one of the many text-books on pure photography that 

 exist if more detailed instructions are required. Particularly if 

 this is the first attempt at any photographic process, recourse 

 must be had to a simple text-book. 



The process in general is as follows. The plate, after 

 exposure, is removed from the dark-slide, and is at once without 

 any preliminary washing put into what is known as the de- 

 veloper. This acts on the plate, and the result of the exposure 

 becomes evident in a shorter or longer time. When development 

 is completed, the salts of silver unacted on and remaining 

 in the film have to be removed ; this process is known 

 as fixing the plate. After fixation is complete, the plate has 

 to be washed for a shorter or longer period, according to the 

 thickness of the film of emulsion on it, until the fixing solution 

 is completely eliminated from the film. The plate is then put 

 on edge in a position free from dust, to dry, and after drying is 

 ready for any printing operation. 



The number of developers is practically unlimited, and 

 it is best at once to realise that there is very little virtue in 

 any particular developer, but that it is rather a question of the 

 manner in which the developer is used. Assuming that exposure 

 has been correct, development may be conducted with compara- 

 tive ease, and, provided a sufficiently long time is allowed 

 for the developer to act, a satisfactory negative is likely to 

 result. There are three methods now used for ascertaining 



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