CHAPTER XII. 
APPEARANCES OF A PLATE DURING DE¬ 
VELOPMENT AND AFTER FIXATION. 
REDUCTION. INTENSIFICATION. 
T F we carefully notice and properly understand the 
various appearances presented by a plate under¬ 
going development, we shall have the best of all clues 
as to whether the plate has been properly exposed, or, 
if not, in what direction error has been made. And if we 
fail to apprehend the true state of matters during 
development, we may arrive at a sound conclusion after 
the plate is fixed, when we can examine it in good light. 
As stated in last chapter, the metol developer causes 
the image almost to flash up immediately after applica¬ 
tion ; the pyrogallol developer acts less rapidly, and 
the hydrokinone considerably more slowly, than the 
pyro, but when we have arrived at the normal rapidity 
of action with each of these developers, we are in a 
position to judge whether we have erred in exposure^ 
and, if so, in what direction. 
If the image comes up too soon, and is grey all over 
almost at the first, we may know that we have over¬ 
exposed. 
