BITTER ROOT 47 BIZERTA fruits, with a thin, fleshy rind; the ker- nel is bitter and uneatable. BITTER ROOT, lewisia redivlva, a plant of Canada and part of the United States, order mesembryacese, so called from its root being bitter though edible, It bears a solitary rose-colored flower. The plant appears above gi-ound for only about six weeks. California bitter- root (echinocystis fabacea) and Natal bitter-root (gerrardanthus macrorhiza) both belong to the gourd family. BITTER ROOT MOUNTAINS, a range of the Rocky Mountains, in Mon- tana, deriving its name from a plant with rose - colored blossoms, whose slender roots are used by the Indians for winter food. The chief summits are Lolo Peak and St. Mary's Peak. BITTER ROOT RIVER, a tributary of the Columbia in Montana, flowing N. into Clark's river in Missoula county; length about 110 miles. Gold has been found in this region. BITTER ROOT VALLEY, on the E. of the Bitter Root Range, in Montana, is 90 miles long and 7 miles wide, enwalled by lofty mountains, and abounding in farms and cornfields. BITTER SALT, Epsom salt, sulphate of magnesia. BITTER SPAR, rhomb-spar, the crys- tallized form of dolomite or magnesian limestone. BITTER SWEET, the woody night- shade, soldnnm dulcamara. BITTER VETCH, a name applied to two kinds of leguminous plants, (a) erviim ervilia, a lentil cultivated for fod- der; and (b) all the species of orobus, e. g., the common bitter vetch of Great Britain, O. hiberostis, a perennial her- baceous plant with racemes of purple flowers and sweet, edible tubers. BITTER WOOD, the timber of xylopia glabra and other species of xylopia, or- der anonaceae, all noted for the extreme bitterness of the wood. The name is also given to other bitter trees, as the bitter ash. yellow gentian BITTER-WORT, {gentidna lutea). BITUMEN, a mineral substance, re- markable for its inflammability and its strong, peculiar odor; generally, how- ever, supposed to be of a vegetable or- igin. The liaima, which was in use among the ancient Romans, is variously employed, sometimes to include a num- ber of the substances called mineral res- ins, particularly the liquid mineral sub- stances called naphtha and petroleum, or mineral oil, and the solid ones called mineral pitch, asphalt, mineral caout- chouc, etc. BITUMINOUS COAL, coal which burns with a yellow, smoky flame, and on distillation gives out hydrocarbon or tar. It contains from 5 to 15, or even 16 or 17 per cent, of oxygen. See Coal. BITUMINOUS SCHIST, schist im- pregnated with bitumen; occurs in the Lower Silurian rocks of Russia. Sir R, Murchison considered that it arose from the decomposition of the fucoids im- bedded in these rocks. BITUMINOUS SHALE, an argilla- ceous shale impregnated with bitumen, which is very common in the coal meas- ures. BIVALVES, those moUusks whose coverings consist of two concave shelly plates or valves united by a hinge. A vast majority of recent bivalve shells belong to Cuvier's testaceous order of ascephalous mollusca, the lamellibran- chiate mollusca of Owen, although with them are some classed as multivalves, on account of accessory valves which they possess. There are also mollusks of the class brachiopoda or palliobran- chiata, which possess bivalve shells, as the terebratxdss, or lamp shells, etc. A very large proportion of the bivalve shells of the older fossiliferous rocks be- long to the brachiopoda. BIVOUAC, an encampment of soldiers in the open air without tents, each re- maining dressed and with his weapons at hand. BIZERTA, a fortified seaport of Tunis, the most northern town of Af- rica; at the extremity of a bay formed by Capes Ras-el-Zebib and El-Arid. The town is built on the shore of a lake which communicates with the sea by a canal; and in the time of Barbarossa it was a city of great strength and mag- nificence. The lake is the chief source of trade, as it abounds in many valu- able kinds of fish. Besides the fishery there are valuable coral, grape, olive, and pottery industries. The port is sur- rounded by walls and defended by two castles. Bizerta steadily declined in com- mercial and political importance till 1892, when the French Government be- gan converting it into a nxagnificent naval port. It is now large enough to accommodate at one time all the navies of the world. A canal was also con- structed through the Isthmus of Zar- zana, connecting the lake with the Medi- terranean.
