174 W. Crookes on the Waz-paper Photographic Process. 
cause a stain. Should this happen, either dry it with blotting 
paper, or immerse the sheet entirely in the liquid. 
50. If the paper has been exposed to a moderate light, the 
picture will begin to appear within five minutes of its being laid 
on the solution, and will be finished in a few hours, 
however sometimes be requisite, if the light has been feeble, to 
prolong the development for a day or more. If the dish be per- 
fectly clean, the developing solution will remain active for the 
whole of this time, and when used only for a few hours, will be 
cuikee appearance indicates the presence of dirt. The progress 
of the development may be watched, by gently raising one cor- 
of producing stains on the surface of the picture. I prefer 
allowing the development to go on, until the black is rather 
yellow iodid of silver has been dissolved out. This operation — 
need not be performed by yellow light; daylight is oe bettter | 
for shewing whether the picture be entirely fixed. This will 
take from a quarter of an hour to two hours, according to the 
time the bath has been in use. 
It will be well not to put too many sheets into the bath at once, 
in order to avoid the necessity of turning them over to allow the 
liquid to penetrate every part. ts 
When fixed, the sheet if held up between the light and the 
eye, will present a pure transparent appearance in the white 
The fixing bath gradually becomes less and less active by use, 
and then its action is very energetic on the dark parts of the 
picture, attacking and dissolving them equally with the un- — 
changed iodid. When this is the case it sould be put on one 
side, (not thrown away,) and a fresh bath made. ai! 
53. After removal from the fixing bath, the sheets must be 
well washed. In this operation, the effect depends more upon — 
the quantity of water used, than upon the duration of the immer: _ 
