A bulk sample is fed with a liquid into a mixing tank (1) where it is stirred to form a dispersion. A proportion of the dispersion is recycled from the bottom of the tank through a line to the top of the tank so that at least the dispersion in the recycle loop (3) is substantially homogeneous, and a representative sample of the dispersion is taken from the recycle loop, e.g. using a slurry sampler (5).