<p>An apparatus for dissolving or suspending a substance in a solvent comprising an outer chamber for containing a dense gas; an inlet for supplying dense gas as a solvent; a porous chamber within the outer chamber for containing a substance for dissolution or suspension with the solvent, the porous chamber having a wall which allows passage of solvent and the substance dissolved or suspended in the solvent, and an outlet for removing solvent and solution and/or dispersion from the outer chamber and a turbulence means for creating turbulence within the porous chamber. A method of dissolving or suspending a substance, and fine particles formed from the resulting solution or suspension are disclosed.</p>
