The Dictionary Of Photography

A True Historic Record Of The Art & Practice Of Photography 100 Years Ago.

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Intensification
The hydrochloric acid should be placed on the powdered mercuric chloride, and then the water added. The negative to be in-tensified, having been previously treated as above suggested, should be laid in the solution, and the dish gently rocked till on looking at the back of the plate it is seen to be quite white. It should then be thoroughly washed for at least 20 minutes in running water, and then immersed in one of the following solutions : -
I.
Sodium sulphite (cryst.)........, 1 part.
Water           .........          ..... 6 parts.
II. The ordinary ferrous oxalate developer.
Hydroquinone developer.
IV.
Strong Liquid ammonia
1 part.
Water ......
V.
10 parts.
Silver nitrate
... ... ■<
20 parts.
Distilled water
•.• ... . •
. 500 ..
and add gradually
Potassium cyanide ...
... ...
20 parts.
Distilled water
... ...
. 500 ,,
Shake well after each addition, till only a small quantity of white flocculent precipitate remains. It is important that the solution should never be quite free from sediment.
VI.
Potassium cyanide ... ,,         iodide
409