The presence of dissolved gas, in the form of very small bubbles in the aqueous phase between a solid particle interacting with a microbubble, and/or on the surface of the particle, modifies the van der Waals interaction forces. The change in the character of the latter appears similar to the action of hydrophobic forces. Neglecting these changes can lead to the incorrect interpretation of experimental data, in particular to the overestimation of the role of any hydrophobic attraction.