J&~S& 5&, where J&z depends on the parameters of the conduction electrons and on the distance between the ionsi and j. However, because of the nonlinear response of the conduction electrons to the effective field of the localized spins in our theory, the Hamiltonian (2), if expressed in terms of an exchange interaction between the spin operators of the magnetic ions, would contain terms of higher orders in the product S, 5& than the bilinear term in the RKKY Hamiltonian.It is well known that such terms can produce first-order magnetic phase transitions. Phys. Rev. 178, 783 (1969). M. A. Rudermann and C. Kittel, Phys. Rev. 96, 99 (1954). 2To simplify the equations, we employ beginning with Eq. (9) a system of units in which 52/2m* =1, where m* is the "effective mass" of the conduction electrons. '3J. H. Van Vleck, Rev. Mod. Phys. 34, 681 (1962).We report magnetic susceptibility studies of dilute liquid alloys containing V, Cr, Mn, Fe, Co, and Ni in Cu, CuZn, Zn, ZnGa, Ga, GaGe, Ge, GeAs, and As liquid solvents. An analysis of the susceptibilities in terms of excited local impurity configurations (excited impurity pseudoatoms) offers a quantitatively successful and conceptually clear insight into the magnetic properties of impurities in simple metallic host lattices at high temperature.