In using hot-film anemometry for turbulence studies in water and in studying reaeration in water with no oxygen demand, there is a need to remove dissolved gases from water. This may be accomplished by putting the water into an environment in which it is supersaturated. For example, the water may be heated or sprayed through an evacuated air space, so that it tends toward saturation in the altered environment. The same principle may be applied in another relatively inexpensive and convenient method which has the advantage that it can be used continuously while experiments are under way.