Abstract: A physical property of the solid component of a slurry, for example the percentage content of a selected element such as iron, is continuously measured. A sampling device (2) carrying a filter element is immersed in the slurry at a sampling station (A). Vacuum is applied to the sampling device (2) to cause the liquid content of the slurry to pass through the filter element, leaving the solid component deposited on the filter element as a filter cake. The sampling element is transferred to a heating station (B), where the filter cake is dried, and then to a measuring station (C), where the desired physical property is measured. The sampling device is then transferred to a washing station (D), where the filter cake is washed from the filter element so that the procedure can start again. The process is automatically controlled by a microprocessor, enabling continuous sampling of the slurry to be carried out.