134 PHOTOGRAPHIC FACTS AND FORMULAS 
Germany by the Aktiengesellschaft f. Anilinfabrikation. A 
similarly acting solution can be made as follows: 
Mercuric chloride 187 g 3/02: 
Hot water 750 ccm 12 oz. 
Add: 
Ammonium sulphocyanide 225 ¢ 3 0z., Z02'ee 
Water 250 ccm 4 oz. 
For use dilute 1 part with 10 parts of water. The negative 
turns black at once; but, if left too long, the intensification is 
reduced. The images are not stable unless a developer is 
applied. 
THE CHROMIUM INTENSIFIER (Eder, Welborne Piper and 
Carnegie)—This method of intensification has deservedly 
received considerable attention, being less liable to stain and 
much less poisonous than many others. The negatives need 
not be absolutely free from hypo, as the bleaching bath 
oxidises this, though, if much hypo be present, it may be 
necessary to apply the bleaching bath twice. Two stock 
solutions are required: 
I. Potassium bichromate 50 g 384 gr. 
Water 1000 ccm 16 oz. 
II. Hydrochloric acid, pure 100 ccm lL oz. 
Water 1000 ccm 10 oz. 
The bleaching baths are: 
A B c 
Stock solution I 32 64 64 parts 
Stock solution IT 3 16 64 parts 
Water 128 fe RO 32 parts 
Immerse the negative in the solution until the image on the 
glass side appears bleached, then wash until the yellow stain 
is removed, and develop with amidol in white light. Other 
developers may be used, without bromide, but the image 
requires exposure to diffused daylight, and they are less 
a 
