as to provide a very small amount of forward flow a typical forward pressure is one atmosphere u00b1 1 2 inch of water therefore in order to maintain this constant pressure in the reactor waste gases must flow into tube 18 at essentially the same pressure in order to avoid back pressure upstream in order to assure a uniform mixture fuel gases in laminar flow through take 18 are mixed with turbulently flowing air which enters through opening 4 it has been found that when high velocity air flowing through pipe 2 reaches inlet 8 it meets with low velocity gases in pipe 2 a portion of the air therefore enters inlet 8 hits the side wall of pipe 10 at point 26 and centrifugally swirls in the direction of arrow 28 in a preferred embodiment the gases which flow through tubes 18 are at least combustible and are usually pyrophoric since pyrophoric gases ignite spontaneously when contacted by air a separate ignition source might not normally seem necessary however to assure combustion the invention provides ignition means 16 as added reliability for the apparatus furthermore when merely combustible gases such as hydrogen are used an ignition source certainly is desired if not necessary to add further reliability to the apparatus the ignition spark plug 16 may be provided with a platinum tip to catalyze ignition when hydrogen.