94 PHOTOGRAPHIC PROCESSES. 



a less intense negative, use more silver and same 

 amount of gelatine. 



Always use the same number of grains of bromide 

 of ammonium in the brine as you use silver in the 

 gelatine, and reduce or increase the carbonate of 

 soda and citric acid in same proportion you reduce 

 or increase the silver. Always use the same amount 

 of gelatine. Any water that is fit to drink is fit to 

 make emulsion. Water that is strong of lime is not 

 good. 



The plates being prepared by Hartley's formulas 

 or purchased, the following methods, of development 

 are recommended; a dish, preferably of ebonite, just 

 large enough, to hold a quarter plate, and another 

 of the same material to hold four or a larger number 

 are obtained, (a great saving both of time and solu- 

 tion being affected if several plates, which have each 

 received a similar exposure, are developed at the 

 same time.) Also a dish of earthenware to hold a 

 saturated solution of alum, another for a similar 

 solution of mercuric chloride, and one for hyposul- 

 phite of soda or fixing solution : these should all 

 differ in appearance, to avoid the possibility of 

 putting a solution into one, which had previously 

 contained another. 



The dishes being placed in a convenient position 

 in the dark room, one or two plates according to 

 circumstances are placed in the dark slide; every 

 precaution being taken during this and all subse- 

 quent operations for the exclusion of actinic light. 

 The exposure being made, the slide with its contained 



