While the plate is still wet, dip it into a solution that contains silver nitrate. The silver nitrate binds with the iodide and bromide to make a silver halide coating, which is sensitive to light.

Carbonate ions also produce a white precipitate with silver nitrate solution. The acid reacts with any carbonate ions present. This removes them, so stopping them giving an incorrect positive ...

The primary difficulty is that the addition of small amounts of silver nitrate to urine results in the formation of colloidal silver halides. Craig and Jackson 1 overcame this by the addition of ...