100 PRACTICAL PHOTOMICROGRAPHY. 



b. Sodic hydrate " caustic soda " 80 grains 



Water (that has been boiled) 10 ounces 



The developer consists of equal parts of a and 5. 



The action of this developer is on the whole more gradual 

 than that of a pyro-ammonia developer; the density varies 

 chiefly as the exposure, and the shadows have a tendency to 

 develop more slowly and with greater clearness than when 

 pyro is used. 



The carbonates may also be used with hydroquinone, but 

 such a developer is much less energetic than the above. 



The writer frequently uses potassic meta-bisulphite in place 

 of the citric acid and in less quantity. 



Potassic hydrate is as good as sodic, or better. It is well for 

 the beginner to use the above solution somewhat diluted, say 

 with an equal measure of water. 



