. . . . "roup consisting of a --SO3 M group, a --COOM group and a --PO(OM')2 group, in which M is hydrogen or an alkali metal and M' is an alkali metal or a hydrocarbon radical, a second magnetic material comprising a second magnetic iron oxide in which the atomic number ratio of a divalent iron component Fe2+ to a trivalent iron component Fe3+ is 0. 001???Fe2+ /Fe3+ ???0.1, and a lubricant; and wherein sa" . . . . .