Physicochemical Property: White monoclinic crystal, relative density 1.72, melting point 73 ° C, at 75 ° C at the beginning of dehydration, at 135 ° C when the decomposition of the formation of basic salt, the temperature is higher than 500 ° C completely decomposed into alumina and nitrogen. Soluble in water and methanol, ethanol, glycerin, insoluble in arsenolite acridine, has hygroscopicity. Uses: mainly used in the manufacture of a catalyst for organic synthesis, textile industrial mordant, leather tanning agents, anti-corrosion inhibitors, anti-sweat agent, solvent extraction Recycling nuclear fuel, etc., when salt analysis.