APPEARANCES OF A PLATE, ETC. 
129 
to each pint of which add a dram of hydrochloric acid. 
Soak the plate in this till the him is greyish white all 
over and through to the back, and wash well. Prepare 
a weak dilution of liq. ammonise, just smelling dis¬ 
tinctly of the ammonia, and immerse the plate in 
this till the image is black or dark brown right 
through to the back of the him, then wash. If any 
stain appears in this operation the plate has not been 
thoroughly freed from hypo. In place of the ammonia 
a weak solution of sodium sulphite may be used; this 
is safer as regards staining, but does not give so strong 
intensification as the ammonia. If, after either ammonia 
or sulphite, a scum appear on the plate, it may be 
removed by rubbing with a small pad of cotton-wool. 
It is most important to let the second solution act till 
the action has gone right in through the him : if this is 
neglected there is grave danger of the negative going 
wrong after a time. In place of either ammonia or 
sulphite alone to follow the mercury, one part of the 
hydrokinone stock solution (A), page 119, to two or 
three parts of water may be used. This will give a 
dense, ruddy image, printing with great contrast. 
Several solutions are now on the market, to be used for 
intensifying negatives or positives on glass. Of these 
we can recommend from experience two—the “Agfa” 
Intensiher of a Berlin krm of high reputation, and the 
“ Intensifying Solution ” of Kodak Limited. Both are 
poisonous. 
It is not necessary to reduce before intensifying, but 
the two operations afford the best means known to us of 
