Patent ID: 7591452

Claim:
A method for producing bubbles by the injection and dispersion of a gas through a porous body into a liquid, wherein the porous body has a value of 1 to 1.5, wherein the value is given by dividing the pore diameter that accounts for 10% of the total pore volume in the relative cumulative pore distribution curve of the porous body by the pore diameter that accounts for 90% of the total pore volume in the relative cumulative pore diameter distribution curve of the porous body, wherein the contact angle with respect to the liquid of at least the surface of the porous body that is in contact with the liquid is greater than 0° and less than 90°, wherein the gas is pressurized so that (1) the pressure is not less than the minimum pressure ΔPc given by the following equation; Δ Pc= 4γ cos θ/ Dm wherein γ is the surface tension of the liquid relative to the gas, θ is the angle of contact relative to air of the liquid present at the surface of the porous body, and Dm is the average pore diameter of the porous body, and (2) the pressure difference ΔP between the pressure of the gas when the gas is pressured and the pressure of the liquid is controlled to 0.2 to 10 MPa.