178 W. Crookes on the Wax-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 a time, 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 

 be obviated, and with very slight sacrifice of accuracy, by form- 

 ing an artificial or secondary negative in the following manner : 



69. Print a copy on positive paper, of any intensity which will 

 show the most distinct impression ; then without fixing, and with 

 a pair of sharp scissors, accurately and carefully cut out the part 

 corresponding to the impressed portion of the negative. Expose 

 this piece to the light until it has become perfectly opaque, and 

 then it can either be cemented over the imperfect original sheet, 

 or on a clean sheet of paper, and used as an ordinary negative. 



It is astonishing what accuracy and quickness in cutting even 

 the most intricate pictures, may be obtained with a little practice; 

 the error of the scissors is generally within the error of meas- 

 urement. 



