Abstract: Hafnium containing preceramic polymer is made through the reaction of hafnium halide compound with any of the following compounds: ethylene diamine, dimethyl ethylene diamine, piperazine, allylamine and or polyethylene-imine.

Abstract: An apparatus for controllably mixing air with a combustible gas to form a combustible mixture. The apparatus includes a housing having an internal gas mixing chamber in communication with an elongated narrow gas inlet throat which is formed by a pair of converging, smoothly curved walls. A gas injector manifold is disposed proximate the gas inlet throat and is arranged so that air flows around and about the injector as it is drawn into the inlet throat either by a fan or through aspiration. Due to the novel aerodynamic shape of the walls which form the gas inlet throat, the combustible gas is thoroughly and efficiently mixed with the air to produce a combustible mixture that burns efficiently with a minimum of harmful emissions being produced.