178 W. Crookes on the Waz-paper Photographic Process. 
fixed. After this time, its stay need only be prolonged until it 
has become of the desired tone and color; always remembering, 
that during the subsequent operation of drying, &c., it will — 
become of a somewhat darker tint than when taken out of the 
fixing bath. | 
66. On removal from this bath, the pictures must be allowed 
to soak in a large quantity of cold water for ten or twelve hours, 
There must not be very many in the dish at atime, and the 
water must be changed at least three times during that interval; 
they must then have boiling water poured over them (of course — 
in a porcelain dish) two or three times, and lastly pressed dry, 
between sheets of clean blotting Paper (14), (these may be used 
several times, if dried,) and then allowed to dry spontaneously © 
in the air. When the pressure frame is not in use, a pile of these — 
finished positives may be put in, and kept tightly screwed up all 
night; by this means they will be rendered perfectly flat and 
smooth. 
67. The picture is now complete. It must be borne in mind, — 
however, that the light and shade are reversed by this operation, — 
the track of the luminous image along the paper being repre- 
sented by a white instead of by a black band, as in the original — 
negative. Should it be desired to produce exact facsimiles of — 
the negatives, it can be done by employing one of these positives — 
as a negative, and printing other positives from it; in this way, 
the light and shade having been twice reversed, will be the same 
as in the original negative. 
68. In some cases it may happen, that owing to a partial 
failure of gas, or imperfection in the sensitive sheet, an image 
may be so faint as to render it impossible to print a distinct posi- 
tive. The gap that this would produce in a set of pictures may 
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