Process for the preparation of aqueous magnetic material suspensions

A process for the preparation of magnetic fluid of a suspension of a ferromagnetic iron material in an aqueous medium which comprises mixing a petroleum sulfonate in the aqueous medium, dissolving an iron compound in the aqueous medium, adding an alkali to the aqueous medium, and reacting the mixture at a pH in the range of 5.5 to 8 to form magnetic iron oxide or magnetic hydroxyoxide, said iron being present in the aqueous medium as ferric and ferrous forms, and said petroleum sulfonate being mixed in an amount sufficient to disperse the iron oxide or iron hydroxide.