White, yellowish powder or six party crystallization. Without odour. Bitter taste. Under normal pressure can sublimate. Can absorb carbon dioxide from the air. Heated to **0 ℃ color to become yellow, but after cooling into white again. Soluble in dilute acetic acid, mineral acid, ammonia, hydrogen and ammonium carbonate oxidation alkali solution, hardly soluble in water. The relative density of 5.*7 (six party crystal), (d**4) 5.**7. Melting point more than ***0 ℃. Refractive index (nD) 2.***1 (2.***3).

Store in a cool, well-ventilated area. Away from the fire, heat source. Should be stored apart and antioxidant, avoid by all means is mixed store. Storage areas shall be with the right material for leakage content.