Ammonium Platinonitrite, (NH₄)₂Pt(NO₂)₄

Ammonium Platinonitrite, (NH₄)₂Pt(NO₂)₄.2H₂O, which is obtained in solution by double decomposition of solutions of ammonium chloride and the silver salt. Upon evaporation it crystallises in colourless or faintly yellow rhombic prisms, which are stable in air but become anhydrous in vacuo. Upon heating, it decomposes with considerable violence, the mass becoming incandescent and swelling considerably, leaving a bulky mass of platinum sponge.