oct. — -dec. 1856.] Paper Process in Photography. 75 



ing, or developing papers is in progress. This we will call the 

 operating room. 



Where circumstances permit, the best light is obtained through 

 a ruby coloured glass, made for this purpose, one or two moderate 

 sized panes of this should be fitted into a window or door, if 

 possible at the level of the table, that being the most convenient 

 direction of the light in many Photographic operations. The light 

 thus procured will not affect Collodion (unless the sun shines upon 

 the glass) and is so abundant as to permit everything to be seen 

 with the greatest comfort. Where this mode of fitting up a room 

 cannot be adopted, a double fold of long cloth, or close woven 

 country cloth, dipped in an aqueous solution of Turmeric, and made 

 to sit close to the wall, makes a curtain that obstructs the actinic 

 rays, and admits a considerable amount of light, but not so much 

 as the glass. 



To EXCITE EOE, THE CaMEKA. 



The exciting solution consists of, 



Distilled water .....c ...oz. 1 



Crystallized Nitrate of Silver ,grs. 25 



Glacial Acetic Acid (half a fluid dram) mins. 30 



This solution should either be kept in a yellow glass bottle, or 

 in a bottle with a wooden or dark pasteboard cover, as although 

 Aceto-nitrate of Silver is not liable to be decomposed by daylight 

 when the chemicals are pure, it becomes so after contact with the 

 organic matters contained in the iodized paper. 



Filter as much of this solution as will cover the dish to the depth 

 of a quarter of an inch. Float the marked side of the paper on it 

 for four minutes — taking care that there are no air-bubbles* 

 These, if any exist, will be indicated (in from 30 to 60 seconds,) 

 by that part of the paper remaining of a dark colour-^ whilst the 

 remainder is becoming white (apparently, but in reality of a prim- 

 rose yellow colour.) Have ready a dish with distilled water and 

 float the excited paper on it for a minute or two, this removes the 

 excess of Nitrate (perhaps some Nitrate of Potash, &c), and makes 

 the paper keep longer without becoming discoloured. On a clean 

 table, or a board kept for the purpose, put 3 or 4 folds of blotting 



