  This paper compares theory and experiment for the kinetics of time-dependent
sedimentation. We discuss non-interacting suspensions and colloids which may
exhibit behavior similar to the one-dimensional motion of compressible gas. The
velocity of sedimentation (or creaming) depends upon the volume fraction of the
constituting particles and leads to Burgers-like equations for concentration
profiles. It is shown that even the bi-dispersive system of two coupled Burgers
equations has rich dynamics. The study of polydispersive case reveals a
continuous ``renormalization'' of the polydispersity. We compare the Burgers
system evolution with the experimental results on mono- and polydispersive
sedimentation. The influence of thermal fluctuations is briefly discussed.
