Ferric hydroxide 
 Gel electrophoresis chemical formula Fe (OH) 3, brown or reddish-brown powder or dark brown flocculent precipitate. Density of 3.4 ~ 3.9g/cm3. Alkaline with gender but its stronger than the acid, the new system was the iron hydroxide soluble in inorganic acids and organic acids, can also be dissolved in hot concentrated alkali. Strong oxidants such as sodium hypochlorite, in alkaline medium, can the new system of ferric oxide into + Ⅵ high oxidation state of iron sodium Na2FeO4. Gradual decomposition when heated from iron oxide and water. Insoluble in water, and ethanol, soluble in acid, the solubility in the acid made in the length of time, depending on the new system soluble in acid, if the place a long time, it is hard to dissolve. Ferric hydroxide can be used to control paint, drugs, also can be used for arsenic antidote, and so on. By the soluble Fe (Ⅲ) salt solution plus ammonia ferric hydroxide precipitate from the system or by ferric chloride, ferric nitrate solution by adding ammonia precipitate in the system.