PHOTOGKAPHIC PKOCESSES 243 



satisfactorily with any plate ; or an amidol developer may be 

 substituted a suitable one is as follows : 



Amidol . ".'":.. 5 grammes. 



Sodium sulphite : . 50 grammes. 

 Water . .' . .to 1000 c.c. 



This solution should be made up as required. 

 Make a stock solution as follows : 



Sodium sulphite . . 200 grammes. 

 Potassium metabisulphite . 25 grammes. 

 Water . . . to 1000 c.c. 



When required for use, take dry amidol and add two to 

 three grains to each ounce of the above. 



The first developer will only keep for two to three days at the 

 outside, and a stock solution should therefore be made up and 

 the amidol added dry as described in the second case. 



An alternative, and almost universal developer, is as 

 follows : 



Solution 1. 



Potassium metabisulphite . 2 grammes. 



Ortol .... 1 gramme. 



Hydroquinone ... 1 gramme. 



Distilled water . . 600 c.c. 



Solution 2. 



Potassium carbonate . . 60 grammes. 

 Distilled water . . . 600 c.c. 



For use, take equal parts of solutions Nos. 1 and 2. 



Development is carried out in exactly the same manner as 

 negative-making; but the process must be carried as a rule 

 only far enough to give a bright-looking positive. No part must 

 be so dense that when it is projected on to the screen it will not 

 allow light from the projection apparatus to penetrate. Some 

 little experience is necessary before a good lantern-slide can 

 be produced; but once this experience is acquired, there is no 

 particular difficulty. In any case, a good slide should have 

 at least some small part in which there is, on fixing, absolutely 

 clear glass. Development is usually much more rapid than 

 when making a negative, and the beginner will probably err on 

 the side of over-development. 



K 2 



