The (Fe)(OH)3 Ion Product in Suspensions of Acid Soils

In suspensions of seven acid soils, the (Fe)(OH) 3 ion product was constant after 139 days at a mean value of 1 (± 0.5) × 10 −39 . Varying the soil/suspension ratio from 1:10 to 1:1,000, as well as changing the concentration of calcium chloride from 0.01 to 0. 1 M had no significant effect upon the (Fe) (OH) 3 ion product. This ion product agrees well with recently reported solubility products of amorphous iron (III) hydroxide.