MORTAR, a chemical utensil, very useful for the division of bodies, partly by percussion and partly by grinding. Mortars have usually the form of an inverted bell. The matter intended to be pounded is put into them, and there struck and bruised by a long instrument denominated a pestle. The motion given to the pestle ought to vary according to the nature of the substances to be pounded. Those which are easily broken, or which are apt to fly out of the mortar, or which are hardened by the stroke of the pestle, require that this instrument should be moved circularly, rather by grinding or bruising than by striking. Those substances which are softened by the heat occasioned by rubbing and percussion require to be pounded very slowly. Lastly, those which are very hard, and which are not capable of being softened, are easily pounded by repeated strokes of the pestle; they require no bruising but when they are brought to a certain degree of fineness. But these things are better learned by habit and practice than by any directions. MORTAR, in the military art, is a short cannon of a large bore, with chambers; it is made of brass or iron, and its use is to project hollow shells, filled with powder, called bombs, and sometimes also carcasses. (See ARTILLERY.) The mortars used at sea are fixed in bomb-vessels, which are constructed for their reception; they are made somewhat longer and much heavier than those employed on land. See GUNNERY. MORTARA, a province of the duchy of Piedmont, in the continental dominions of Sardinia. It extends over 378 square miles, and comprehends one city, eighty-four towns and villages, and 56,840 inhabitants. It was formerly a part of Milan, and then was denominated Lumelina. It is a level district, watered by the Po, the Ticino, and the Sesia, with their tributary streams, which irrigate the land abundantly, and cause it to yield much rice, which, with silk, forms the chief product. The capital is a city of the same name, and is surrounded with walls. It is situated in a most insalubrious district, much affected by miasma, and contains only 2850 inhabitants. Long. 9. 11. E. Lat. 45. 16. N. MORTIER, an ensign of dignity, which was borne by the chancellor and grand presidents of the parliament of France. That borne by the chancellor consisted of a piece of cloth of gold, edged and turned up with ermine; that borne by the first president was a piece of black velvet edged with a double row of gold lace. MORTISE, or MORTOISE, in carpentry, &c. a kind of joint wherein a hole of a certain depth is made in a piece of timber, which is intended to receive another piece called a tenon. MORTLAKE, a parish of the county of Surrey, in the hundred of Brixton, seven miles from London. It is beautifully situated on the south bank of the Thames, and includes several splendid houses, and a part of the royal park of Richmond. The inhabitants amounted in 1801 to 1748, in 1811 to 2021, in 1821 to 2484, and in 1831 to 2698.