Plumbic acetate gives a purplish-red precipitate, mercuric cyanide a blue one, the supernatant liquid being also blue.
Plumbic sulphide is precipitated, and the liberated selenic acid separated by filtration is concentrated until it acquires a sp.
The residue dissolved in water is mixed with a solution of plumbic nitrate, an insoluble plumbic seleniate being precipitated.
The plumbic seleniate is suspended in water and decomposed by means of a current of sulphuretted hydrogen.
Chemically it is converted by nitric acid and chlorine into an insoluble substance--plumbic acid or the cyanide of lead.