Decreasing the size of the laboratory sample or individual particles, or both. Division of the size of the laboratory sample may be accomplished manually by coning and quartering or by riffling or mechanically by rotary dividers. Reduction of particle size may be accomplished by milling or grinding. Simultaneous division and reduction may also be achieved with mills having stream diverters.
PAC, 1990, 62, 1193. 'Nomenclature for sampling in analytical chemistry (Recommendations 1990)' on page 1204 (https://doi.org/10.1351/pac199062061193)