The gas velocity interval for initiating gas fluidization of binary mixtures of Geldart type B particles has been thoroughly investigated experimentally and theoretically by Formisani et al.([2-6]) The same approach has now been applied in our laboratory to liquid fluidization of binary macro-solids. Experimental results for water fluidization in a 190.5 mm diameter column of initially well mixed packed beds, consisting of different volumetric fractions of 1.91 mm and 4.54 mm glass spheres of density 2510 kg/m(3), are well predicted by the methods of Formisani et al., whether the equations are based on random-dense voidages as practiced by that group, or based on random-loose voidages as commonly used for monocomponent solids.