Preliminary studies were made of the feasibility of using the gaseous diffusion process for the production of enriched isotopes of certain specific elements which are of interest in various phases of the United States' nuclear program. The results of these studies indicate the gaseous diffusion process is probably the most practicable method of separating the isotopes of tungsten, molybdenum, and xenon to produce mnterials with the desired characteristics. In each of these cases one is confronted with the problem of separating the isotopes of a multicomponent mixtare: in the case of tungsten the desired isotope W/sup 184/ is a midd1e isotope in the naturally occurring mixture. 8pecial modes of operntion are required in order to enrich a mixture with respect to a middle isotope. Since all of the considerations which apply to the separation of the various isotopes mentioned above are included in a discussion of the tungsten problem, only the specific problem of enriching the desired isotope of tungsten is discussed. (auth)