OCT. — DEC. 185G.] 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 ah 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 FOR THE CaMEKA. 
The exciting solution consists of, 
Distilled water c oz. I 
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 SO 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 
