Zinc hydroxide are amphoteric hydroxides. Zinc salts dissolved in acid generation. Soluble in strong base generates Zincate. And aluminum hydroxide can be dissolved in the ammonia generated zinc ammonia complex ions: Zn (OH) 2 +4 NH3 = [Zn (NH3) 4] 2 + +20 H-used as rubber additives, surgical ointments. Add appropriate amount of alkali solution prepared by the zinc salt solution.