In this paper, the classical theory of light scattering in homogeneous mediums leading to the Landau-Placzek equation representing the ratio of the intensity of the Brillouin component to that of Rayleigh component. Because of effect dispersion, the simple Landau-Placzek equation is modified by defining hypersonic adiabatic compressibility (β_S)^=1(ρν_)^2,where ν_ is the velocity of hypersonic sound wave which cause Brillouin scattering and obtained from the experimentally measured Brillouin Shift. Authers measure the Brillouin Shifts and the ratio of the intensities with a He-Ne laser light source, pressure-scanning Fabry-Perot interferometer and photoelectric detection anp discuss experimentally techniqes and data disposal procedure. The Rayleigh scattering (central component) is much affected by dusts in samples, so we carefully try to take off it. Predictions are evaluated for 12 liquids and compared with experimental vatues. In most cases, predictions modified with dispersion show better agreement with experimental results than the simple owes. Especially, errors are less than 5 percent for the the ratios of the intensities in acetic acid, carbon disulfide ethyl alcohol, toluene and acetone.