A method for dispersing a gas into a liquid in a reactor, forming a good suspension of the three phases of said gas, said liquid and a pulverulent solid in the liquid and for maintaining the achieved good suspension in the reactor, said method comprising directing a gas jet below the surface of the liquid which contains said solid, by means of at least one flexible-structured dispersing member, said member having solid, imperforate walls with an outlet opening solely at its outermost end, the support point of the dispersing member being above the dispersing member at the bottom of the reactor and at the center point of its operating area, the full gas jet under pressure being dicharged freely from the outermost end of the dispersing member, changing its direction randomly whereby the dispersing member exerts a whip-like, repeating movement at the bottom of the reactor, which movement has a continuously decreasing radius of curvature, at the same time causing strong mechanical mixing and thereby producing a good suspension of the three different phases over the entire cross-sectional area of the reactor.