In this paper degenerate four-wave mixing have been demonstrated using an artificial nonlinear medium a liquid suspension. Using laser pulses from SH of a Q-switched Nd: YAG laser system as pumping beam, the third-order nonlinear optical susceptibility x(3) of the aerosols was measured which is greater than that of CS2 by a factor of 3. The decay time of the density grating was measured by using a continuous reading beam.