Abstract: Gas, such as exhaust gas from a silicon epitaxial reactor, is treated with a liquid such as water. A basin (12) holds a solution (20) including the liquid utilized to treat such gas in the manner intended. An inlet chamber (14) and a convenient self-cleaning passageway (46) introduce the gas into and below a first level (36) of solution (20) established within a treatment chamber (16) in the basin (12). Within delivery piping (44), pressure is provided for advancing the gas for treatment. The treatment chamber (16) is provided with sidewalls (28 and 30) having passageways (46 and 48, respectively), which cooperate with the gas pressure to establish multiple levels (36, 38 and 40) of solution (20) in basin (12) to seal chamber (16). Chamber (16) is also provided with heads (60-67) for spraying the liquid into the advancing gas to wet the same for a time sufficient to treat the gas.