78 PHOTOGRAPHIC PROCESSES. 



After washing and drying, the plate may be var- 

 nished with any of the usual negative varnishes sold 

 by photographers. 



We now proceed to the manipulations necessary 

 for the preparation of the sensitive surface, before 

 exposure in the camera. 



A plate being removed from the dish, it is cleaned 

 as described, (care being taken to avoid touching the 

 surface with the fingers,) then either grasping the 

 right hand upper corner with the thumb and finger 

 of the right hand, or supporting the plate with a 

 plate holder, the collodion is poured on it, form- 

 ing a pool at the same corner, then flowing it to 

 the opposite, then to the left hand bottom corner, 

 and finally after completely covering the plate, off at 

 the right hand bottom corner. The plate being now 

 held in a nearly vertical position over the mouth of 

 the collodion bottle, a gentle rocking motion is im- 

 parted to it to prevent the collodion setting in 

 ridges. When no longer tacky, which is known by 

 barely touching one of the bottom corners with the 

 finger, the plate is placed in the nitrate of silver 

 bath, by a steady downward motion of the dipper, 

 moved about for a few seconds, and finally left for a 

 period varying from one to five seconds, according 

 to the temperature and condition of the solutions. 

 It is then removed, and (after all superfluous fluid 

 has been drained off) placed in the dark slide, ready 

 for exposure in the camera. This should take place 

 as soon as possible, as delay tends to injure the 

 plate. 



