A fountain layer can serve as one of the intensive methods of contacting a solid material with a liquid. While a significant number of works have been devoted to its hydrodynamic regularities in the G‑S system, there is practically no work on the hydrodynamics and mass transfer of the fountain layer in the L‑S system. The lack of a complete analogy in the behavior of these two heterogeneous systems, caused by a significant difference in the viscosity and density of the light phases L and G, urgently requires independent hydrodynamic studies of the fountain layer in the L‑S system...