The convergence of the iterative procedure for solving the slowing down equation is examined. It is found that the rate of convergence of the iterative procedure depends on the ratio of the resonance scattering and absorption cross sections, being rapid if the resonance is predominantly absorbing. The method of Goldstein and Cohen for treating intermediate resonances is carried to the third approximation, and numerical results are obtained for the 192-eV resonance of 238U in a 1:1 mixture with hydrogen.