The Dictionary Of Photography

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Uranium Chloride                                   Uranium Printing
Uranium Chloride (Ger., Uraniumchlorid; Fr., Chlorure d'uranium: Ital., Cloruro di ztranio). Very
soluble in alcohol and water. It has been used for toning and as a sensitive salt for a platino-uranotype process {q-v.\
Uranium Nitrate (Ger., Uranylnitrat, Salftetersaures Uranoxyd; Fr., Azotate d'urane, Nitrate d'urane; Ital., Azotaio di uranio). Uranic nitrate is prepared by digesting pitchblende in hydrochloric acid, to dissolve out the other metals, then roasted with charcoal twice, and the residue dissolved in nitric acid, and purified by crystallisation. It is a brilliant yellowish-green crystalline salt, very deliquescent. Solubility 215 per cent, in cold water, 333 per cent, in alcohol, and 25 per cent, in ether. It is decomposed by light when in contact with organic matter into a uranous nitrate.
Uranium Printing. The colours obtained by the use of uranium salts are decidedly pleasing, tending to a terra-cotta or copper colour, which may be varied at will. The sensitising solution may be prepared as follows : -
Uranium nitrate ............80 grs.
Distilled water ...... ...... 1 oz,
Preserve in the dark. The papers may be floated on this for five minutes, or the solution may be applied with a brush or tuft of cotton wool. The following may also be used: -
Uranium nitrate ...... ...... 80 grs.
Mercuric nitrate ... .........20 ,,
Distilled water         ............ 1 oz.
Or
Uranium nitrate ...... ... ...    80 grs.
Cupric nitrate or sulphate...... ...    20 ..
Distilled water ... ......... 1 oz.
The papers should be exposed under a negative in sunlight until all the principal detail is visible, and then floated on a developer till the tone desired is obtained.
Potassium ferridcyanide ... ...... 50 grs.
Distilled water ............ 1 oz.
This will give a reddish-brown tint.
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