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
minutes.
The exposure under a negative varies from fifteen to twenty minutes in the
shade, and from one to three minutes, at the most, in sunshine. As a
rule, it is advisable to somewhat underexpose in order that the
development be regular, progressive, under control.