the disclosure relates to a method of purifying cadmium and tellurium and forming pure , stoichiometric cadmium telluride therefrom as well as the apparatus for making such cadmium telluride . the cadmium and tellurium are purified by heating each separately to volatilization and passing water in a reducing gas through the volatilized cadmium and tellurium to react with impurities and form gases or precipitates . the cadmium and tellurium are volatilized at different predetermined temperatures such that the amount of each volatilized will be the same so that reaction later takes place with stoichiometric amounts of the elements to form the cadmium telluride . the cadmium telluride is then condensed at low enough temperature so that the remaining gases pass out of the system .