the art of pulverizing, or reducing a dry body into a fine powder. This is performed in friable bodies by pounding or beating them in a mortar; but to pulverize malleable ones, other methods must be taken. To pulverize lead or tin, the method is this: Rub a round wooden box all over the inside with chalk; pour a little of the melted metal nimbly into the box; then shut the lid, and shake the box briskly, when the metal will be reduced to powder.