126 PBACTICAL PHOTOMICROGRAPHY. 



A strong developer (say 4 oxalate to 1 iron) gives good 

 brisk blacks, a weak developer (say 1 to 7) is apt to yield 

 "washed out" tones of the image, while a very weak developer 

 sometimes produces a peculiar appearance of measliness or 

 grain. 



If we have to print a weak, " ghostly " negative, we keep 

 down the exposure and develop with a brisk developer 

 restrained with a full dose of free bromide, say 1 grain 

 bromide per ounce of developer. If our negative is hard or 

 shows violent contrast, we give a prolonged exposure and use 

 a developer consisting of, perhaps, 1 part of iron to 6 of 

 potassic oxalate, and even to this some water may be added, 

 while the free bromide may be reduced, or even omitted. 



One strong point, perhaps the strongest point in favor of 

 this process is that it lends itself above all other printing pro- 

 cesses to the production of good prints from inferior negatives, 

 and enables us to vary to a very marked extent the prints we 

 may obtain from any one negative. A negative showing little 

 more than a ghost of an image may be made to yield a print 

 actually " hard ;" while a negative of the " chalk and soot " 

 order may be made to yield a print of the utmost softness, and 

 these effects may be produced by a mere variation of the ex- 

 posure, assisted or unassisted by intelligent variation of devel- 

 opment. 



The manipulation of bromide paper is simple. After the 

 exposure the sheet of paper is plunged into clean water in such 

 a manner as to prevent formation of air bells ; if bubbles do 

 occur they are easily seen and must instantly be removed by 

 hand or with a clean camel hair-brush. As soon as the paper 

 lies flat in the dish it may be transferred face upwards to the 

 developing dish, or if the same dish is to be used for both 

 operations of soaking and washing, the water only requires to 

 be poured out of the first dish and the paper left in it face up- 

 wards. The ferrous oxalate developer is now poured over the 

 paper. (See page 92.) The developer should be allowed to 

 act until the shadows of the picture show a good pronounced 

 black as seen by the subdued colored light of the operating 

 room. By this time the highest lights should not show any 



