INTENSE ICA TON 135 
satisfactory. A gives the strongest and C the least intensifi- 
cation. The process may be repeated as often as required. 
As a variant the following may be used: 
Chromic acid 2.5/2 197 or 
Sale: 235) o 197 on: 
Water 1000 ccm 16 oz. 
The procedure described above should be followed. The acid 
and salt may be kept in stock solutions, say 10 per cent, and 
mixed as required. 
A convenient form of a dry salt, the chlorochromate, may 
be prepared as follows (Lumiére & Seyewetz) : 
Ammonium bichromate 82¢ 1265 gr. 
Hydrochloric acid, 
spon. 116 364 ccm 12 oz., 160 min. 
Place the acid in an evaporating dish, add the ammonium 
salt, and evaporate until dry. The result will be 100¢ 
(1543 gr.) of ammonium chlorochromate, which may be kept 
in a dry state or in a 10 per cent solution by dissolving in 
1000 ccm (32 oz.) distilled water. Of this, 30 ccm (210 min.) 
should be diluted to 1000 ccm (16 oz.) to form a convenient 
bleacher. The equivalent weights of the potassium salt may 
be used, that is, 100 g or 1543 gr. 
THE CoOPPER-SILVER INTENSIFIER.—This intensifier is par- 
ticularly valuable for black and white or line negatives, and 
gives great intensification. The bleaching solution is pre- 
pared from: 
I. Cupric sulphate ll5¢g 2 oz. 
Hot water 500 ccm Sioz) 
II. Potassium bromide 1S) & 2 OZ. 
Hot water 500 ccm 8 oz. 
Mix and allow to cool. The negative should be bleached in 
this, washed no longer than 2 minutes, and blackened in: 
Silver nitrate 10 per cent solution 
