15 Heavy metal-containing solutions and solids: container E. Stir Raney nickel (also: Urushibara nickel) in the form of an aqueous suspension into hydrochloric acid (Cat. No. 100312) until dissolved (container E). Neither Raney nickel itself nor any filter residues should be allowed to dry out, otherwise they will spontaneously ignite in air. In this context, heavy metal means any compound of antimony, arsenic, cadmium, chromium(VI), copper, lead, nickel and tin, as well as these subtances in metallic form, if they are classified as hazardous (acc. to AbfallverzeichnisV - Waste Catalogue Ordinance, Appendix 3). Other heavy metals should be collected separately.