210 Trans. Acad. Sci. of St. Louis. 



If the object to be photographed is a landscape, consisting 

 mainly of mid-summer foliage, and the plate be a fast plate, 

 like the crown plate of Cramer, the exposure may be made 

 two to four minutes in length. For the first attempt the 

 latter interval is to be preferred. The exposure may be made 

 as much longer as may be desired. It has been successfully 

 tried with exposures of six and eight hours. 



The plate is taken to the dark room and is best developed 

 by the light of a strong lamp. If the exposure has been 

 not over two minutes, the best result will be obtained by plac- 

 ing the bath between two strong lamps. Two Argand or 

 Rochester burners with porcelain shades in contact or nearly so, 

 with the bath in a position of strongest illumination between 

 and below the shades, is an admirable arrangement. The bath 

 should be cool at the start, and it should be in ice-cold water 

 during the development. The bath being rather weak, the 

 development will go on very slowly. 



Various developers have been tried. Pyro has given very 

 poor results, although the same bath would yield brilliant 

 negatives in the dark room. By far the best results have been 

 reached by the use of Cramer's hydrochinon developer, 

 the formula for which may be found in every box of Cramer 

 plates. This formula is : — 



SOLUTION NO. 1. 



Ounces. Grammes. 



Water 25 1000 



Sulphite of soda 3 126 



Hydrochinon a 21 



SOLUTION NO. 2. 



Ounces. Grammes. 



Water 25 1000 



Carbonate of soda 6 252 



The two solutions are to be mixed in equal parts, when used, 

 and are to be diluted to from one-third to one- fifth strength. 

 A few drops of ten per cent, solution of bromide will give 

 brilliancy to the plate, but will not improve definition of 

 details. The bromide may be left out. 



In transferring the plate from the holder to the developing 

 bath, it would seem to be somewhat better to turn the lamps 



