cyanogen

Cyanogen and hydrocyanic acid, recognizable by their odour, indicate decomposable cyanides.

For a connected view of the various compounds of cyanogen employed in the arts, see Prussian Blue.

If cyanogen be given the chance it will take unto itself an atom of hydrogen, producing the deadly hydrocyanic or prussic acid.

Nitrogen, too, though not directly recognized, proves its presence by the lines of cyanogen.