245,497. Valjean, B. Oct. 6, 1924. Open-tray burners; vaporizing-apparatus. - A combustible condition is established at a predetermined point between streams of non- combustibly rich and lean mixtures of gaseous or vaporized fuel and air by movement of one into the other in a direction transverse to the direction of flow. In the combustion apparatus shown in Fig. 1 a cylindrical carburetter 1 is slidable in a casing 20 on angle-sectioned guides 9 until its discharge opening 3 registers with an opening 21 in the base of a fire-box 12. Liquid fuel is supplied to the carburetter by means of a valve-controlled pipe 7 and is vaporized by the reflected heat of the flame. Air enters the carburetter through rows of apertures 5<a> spaced at regular intervals in the carburetter wall 5 so that a series of air-jets A surrounded by envelopes L of lean non-explosive mixture, films E of explosive mixture, and envelopes R of rich non- explosible mixture travel in an atmosphere of vapour towards the opening 3. On reaching the opening a stream of air entering horizontally through an annular slot 11 formed between a ring 4 on the top of the carburetter and a rim 21a on the fire-box 12 causes an intimate mixture to take place so that complete combustion ensues. The casing 20 may be divided by a partition 16. into two chambers to which air under pressure is supplied through separately controlled pipes 30, 31 for passage to the apertures 5a and the slot 11 respectively. Alternatively, the air supply may be induced by the furnace draught through apertures in the door of the casing 20. The gap 11 may be regulated by means of adjustable bolts 25 passing through the ring 4 and engaging the guides 9. Fig. 5 shows a modification in which an oval carburetter 1<e> is clamped between oval cast-iron rings 4e, 4<g> and the ring 4e is formed with a slot 4f for engagement with the track 9<e>. In a further modification, the ring 4e is cast around the upper part of the carburetter. In another construction shown in Fig. 6, the fuel is fed to .an annular vaporizing pan 40 arranged around the upper edge of the carburetter and a stream of air is drawn through a central opening 5<a> in the carburetter. The transverse mixing movement is effected by a baffle 11<a>. Air is admitted through an inlet 41 while the burning operation is being started.