A reaction vessel (reactor) is shown that, filled with metal and placed either within a CVD type furnace or in a housing in fluid communication with the CVD type furnace can produce commercial quantities of a metal halide gas over extended time periods and multiple furnace runs. The control of temperature and the simplicity of this reaction vessel allows temperature differentials between the metal halide gas produced and the CVD type reactor target thus providing differing deposits. The reactor is noteworthy in that no valves, flow restrictors or other equipment which could create corrosion problems is used in the heated/reactive area of the vessel thus producing very high quality metal halide gas.