DEVELOPERS 269 



For Plates. Use A 1 oz., B 1 oz., water 2 ozs. 

 Watkins Factor, 6. 



PYRO SODA (Ilford Formula). 



A. Sodium carbonate (soda crystals) 2 ozs. or 100 grms. 

 Sodium sulphite (crystals) .... 2 ,, ,, 100 ,, 



Potassium bromide 20 grains ,, 2 ,, 



Water up to 20 ozs. 1000 c.c. 



B. Pyro 1 oz. ,, 50 grms. 



Water up to 6 ozs. ,, 300 c.c. 



Nitric acid 20 drops 



For Plates. Take one part of B, make up to 10 parts, and 

 add 10 parts of A. 



B keeps fairly well, but it is preferable to weigh out the 

 pyro required each time as follows : 



A 1 oz., water 1 oz., pyro 2 grains to 4 grains. 



Watkins Factor, 7 (6 for negatives of ordinary contrast). 



Time of Development with 3 grains pyro per oz. : 

 55 F., 6 mins. ; 60, 5 mins. ; 65, 4 mins. 



DEVELOPERS IN CONCENTRATED SOLUTION. Such as Azol, 

 Certinal, Rodinal, and Victol should be diluted for use accord- 

 ing to the instructions supplied with them. They are some- 

 what as follows : 



For Plates. Developer 1 part, water 20 parts. 



Bromide Papers and Fast Lantern Plates. Developer 1 

 part, water 30 parts. 



Gaslight Papers and Slow Lantern Plates. Developer 1 

 part, water 15 parts. 2 drops 10% potassium bromide may 

 be added to each oz. of solution for papers or lantern slides, 

 or even for plates if desired. 



Watkins Factor, 40. 



Time of Development. At 55 F., 8 mins. ; 60, 7 mins. ; 

 65, 6 mins. 



Tank Development. 1 part developer, 100 parts water. 



Time for Tank Development. 55 F., 30 mins. ; 60, 

 25 mins. ; 65, 20 mins. 



The times required for time and tank development vary 

 with the plate, and those given may need reduction by about 

 J or increase even up to double the time given for some plates. 



