PHOTOGRAPHIC PROCESSES. 77 



The developing solutions are made as follows : 



Ferrous Sulphate, 40 grammes. 

 Glacial Acetic Acid, 30 to 40 c.c. 

 Alcohol, q.s. 

 Water, 1 litre. 



The addition to this developer, of a very minute 

 quantity of gelatine (dissolved in water), adds to the 

 density and fineness of the deposit, a very desirable 

 result in Photo-micrography. 



The amount of alcohol in the solution depends on 

 the age and condition of the bath ; with a new bath 

 none is required. 



The iron should be dissolved before the other in- 

 gredients are added. 



When the picture lacks density, the following in- 

 tensifying solution will answer. 



Pyrogallic Acid, 4 grammes. 

 Citric Acid, 4 to 8 grammes. 

 Distilled Water, 1 litre, 

 to this a few drops of 



Silver Nitrate, 2 grammes. 



Distilled Water, 50 c.c. 



must be added immediately before its application to 

 the negative. 



After the plate has undergone treatment with 

 these solutions, the bromides and iodides unaffected 

 by light are dissolved away, by immersing in 



Hyposulphite of Soda, 1 oz. 

 Water, 6 oz. 



