W. Crookes on the Wax-paper Photographic Process. 171 
: room, and hooking the papers on to this by means of a pin bent 
_ into the shape of the letter S. After a sheet has been hung up 
for a few minutes, a oo of blotting paper, about one Ps 
square, should be stuck to the bottom corner to absorb the drop, 
and prevent its drying on the sheet, or it would cause a stain in 
the picture. 
39. While the sheets are drying, they should be looked at 
occasionally, and the way in which the liquid on the surface 
dries, noticed; if it collect in drops all over the surface, it is 
a sign that the sheets have not been sufficiently acted on by the 
iodizing bath, owing to their having been removed from the 
latter too soon. The sheets will usual ly during drying assume a 
dirty pink appearance, owing probably to the liberation of iodine 
by ozone in the air, and its subsequent combination with the 
starch and wax in the paper. This is by no means a bad sign, 
if the color be at all uniform; but if it appear in patches and 
a it shows that there has been some irregular a sorption of 
the wax, or defect in the iodizing, and it will be as well to reject 
sheets so marked. . 
. As soon as the sheets are quite dry, they can be put aside 
in a box for use ata future time. There is a great deal of un- 
certainty as regards the length of time the sheets may be kept 
in this state without spoiling; I can speak from experience as to 
there being no sensible deterioration after a lapse of ten months, 
but further than this I have not tried. 
Up to this stage, it is immaterial whether the operations have 
been performed by daylight or not; but the subsequent treat- 
Ment, until the fixing of the picture, must be done by yellow 
t (0). 
“41. The next step consists in rendering the iodized paper sen- 
_ Sitive to light. Although, when extreme care is taken in this 
_ Operation, it is hardly of any Sop bec when this is performed; 
‘et in practice, it will not be foun convenient to excite the paper 
earlier than about a fortnight before its being required for use. 
The materials for the exciting bath are nitrate of silver, glacial 
acetic acid, and water. Some operators replace the acetic acid 
_ by tartaric acid; but as I cannot perceive the effect of this 
hange except in a diminution of sensitiveness, I have not adopted 
it. It is of little importance what be the strength of the solu- 
tion of nitrate of silver; the disadvantages of a weak solution 
are, that the sheets require to remain in contact with it for a con- 
siderable time before the decomposition is effected, and the bath 
aires oftener renewing ; while witha bath which is too strong, 
time is equally lost in the long-continued washing requisite to 
enable the paper to keep good for any length of time. The 
quantity of acetic acid is also of little consequence. 
