DEVELOPER FOR PLATES 503 



is to be done it is better to buy developer already put up 

 in tubes or packages, one of which is dissolved in the proper 

 amount of distilled water just at the time it is needed. And 

 this procedure is perhaps always advisable if sufficient 

 funds are available. It is, however, somewhat cheaper to 

 make up stock solutions of developer to be kept on hand. As 

 stock developing solutions the Hammer Dry Plate Company 

 recommends the following: 



Pyro Developer. 



Solution No. 1 : 



Pure water 16 oz. 



Sodium sulphite, anhydrous l' 1 /^ oz. 



Solution No. 2: 



Pure water 16 oz. 



Sodium carbonate, C.P. 114 oz. 



Solution No. 3: 



Pure water 24 oz. 



Oxalic acid 15 grains 



Pyro 1 oz. 



To develop use : 



Pure water (winter) 6 oz. 



Pure water (summer) 8 oz. 



No. 1 i/> oz. 



No. 2 I/, oz. 



No. 3 i/ 2 oz. 



Use pure water, distilled, rain water filtered or river 

 water boiled and filtered, in mixing the solutions. Keep 

 the solutions in tightly stoppered bottles. In using crys- 

 tals use twice the weight given. If negatives are too strong 

 use more water, if too weak or thin use less water. If the 

 negatives have too much of a straw color use more of No. 1, 

 but if the negatives have too blue a cast use less of No. 1. 

 All chemicals should be thoroughly dissolved while mixing 

 them. The anhydrous sulphite and carbonate of sodium are 

 much to be preferred. Wash the plates well before placing 

 them in the fixing bath. 



