Abstract: The theoretical model for mono-and multimolecular adsorption on solid surfaces proposed by the author in the previous paper[1] is further studied. By applying the concept of induced polarization ?taking place in the next layer of molecules as suggested by de Boer, and the concept of micro -adsorption states introduced into the model by the author, three groups of multimolecular adsorption isotherm equations are derived, in which the B. E. T. (Brunauer-Emmett-Teller)equation is only a rare special case, and the Langmuir, Freundlich, and Temkin isotherms are transformed under certain conditions as shown in the previous paper. Those equations can be used to describe the different types of physical adsorption isotherms classified by Brunauer. The physical picture of multimolecular adsorption can be considered to involve an uniform liquid membrane with the thickness of a few molecules.