De La Blanchere's Process 1858

Uranium nitrate 25 parts

Distilled water 100 parts

Filter the solution and keep it in the dark.

The paper should be sized with a gelatine solution at 5 per 100 of water,

and, when dry, kept in the dark.(40) It is sensitized by floating five


The exposure under a negative varies from fifteen to twenty minutes in the

shade, and from one to three minutes,
t the most, in sunshine. As a

rule, it is advisable to somewhat underexpose in order that the

development be regular, progressive, under control.

The image is developed by floating, or immersion in

Silver nitrate 2 parts

Distilled water 100 parts

Nitrate acid, C.P. a trace

When the image is intense enough it is washed in several changes of water,

then toned in a solution of gold at 1 per 1,000 of water acidified with

traces of hydrochloride acid.(41)

The following bath develops slowly, and gives very rich purple tones

without toning:

Nitrate of silver 3 parts

Nitrate of uranium 1 part

Nitrate of cadmium 1 part

Alcohol 10 parts

Water 100 parts

Nitric acid traces

The developing solutions should be as little acid as possible, but not

neutral, for then the proofs would be veiled and grayish.

The image can also be developed in a solution of gold, or in a very weak

solution of mercuric chloride at 1 per 10,000. The proof must be

extremely well printed and left for from two to five minutes in the

mercuric solution. If the time of exposure is right, the image will

change but little in the solution, and will take, when treated with silver

nitrate, the most splendid tones.

The proofs should be carefully washed when finished. If they were

developed with silver, they must be immersed in diluted aqueous ammonia,

which will perfectly clear the whites. If developed with chloride of

gold, the water should be heated to 60 to 80 deg. C. (140 to 176 deg.