Bitterfield, a town of Prussian Saxony, in the district of Merseburg, at the junction of the Mulde with the Lober, 17 m. by railway N. of Leipsic; pop. in 1871, 5,043. It is pleasantly situated, and contains waterworks. Railway communication with all parts of the continent has produced within the last few years great industrial activity. There are coal mines and several iron founderies, breweries, and distilleries, and cloth, pottery, machinery, and other articles are manufactured here. The town was founded in the middle of the 12th century by Flemings.
Bittoor. See Bithoor.
Bituminous Shale, a soft variety of argillaceous slate, found usually associated with coal. It contains a variable proportion of bitumen, sometimes so much of it that it will burn. In Mansfeld, Germany, the bituminous schist found immediately over the new red sandstone contains also a small quantity of copper pyrites, and though it yields only 1 1/2 per cent, of metal, it is made to pay a profit by the ore furnishing its own fuel for reduction. Shale is sometimes distilled for paraffine and illuminating oil.-
Bizerta, Or Benzerta (Anc. Hippo Zarytus), a fortified seaport town on the N. coast of Tunis, the northernmost town of Africa, on a gulf which communicates with a lake in the interior; pop. about 8.000. The harbor was formerly commodious, but is now choked up with sand, and receives only small vessels. The adjoining lake abounds in fish, the roes of which, dried and formed into a substance called botargo, are an article of Mediterranean commerce.
Bjorneborg, a seaport town of Finland, in the province of Abo-Bjorneborg, near the mouth of the Kumo, 72 m. N. N. W. of Abo; pop. 7,270. The old town was wholly burned down in 1801; the new town is well and regularly built. It exports pitch, tar, pine, oil, and wooden ware.
Black (called also brittle silver or glance, and stephanite from the Archduke Stephan, mining director of Austria), an ore composed of sulphur 16.2, antimony 15.3, silver 68.5. It occurs in veins with other silver ores at Freiberg in Saxony, at Andreasberg in the Hartz, and at Zacatecas in Mexico. It is also an abundant silver ore in the Comstock lode in Nevada, and occurs in Idaho and in the Reese river and Humboldt mines. Crystals of it have been found altered to pure silver.
Black Flux, a mixture of carbonate of potash and carbon, obtained by deflagrating two or three parts by weight of cream of tartar (or crude argol) and one part of nitre in a red-hot earthen crucible. If equal weights of these substances be taken, the nitric acid of the saltpetre will oxidize the carbon, and the result will be a pure carbonate of potash, or white flux. When black flux is fused with the oxides of copper, iron, or lead, or with the acid compounds of those metals, the carbon acts as a reducing agent, while the carbonate of potash takes up the impurities, such as sulphur and silica. The reduced metal collects in a button in the fluid slag, and on cooling can be easily separated from its matrix. Black flux must be kept in closely stoppered bottles, as it rapidly deteriorates by absorption of water from the air.