BAUXITE, a substance which has been considered to be a mineral species, having the composition Al2O(OH)4 (corresponding with alumina 73.9, water 26.1%), and thus to be distinct from the crystallized aluminium hydroxides, diaspore (AlO(OH)) and gibbsite (= hydrargillite, Al(OH)3). It was first described by P. Berthier in 1821 as “alumine hydratée de Beaux,” and was named beauxite by P.A. Dufrénoy in 1847 and bauxite by E.H. Sainte-Claire Deville in 1861; this name being derived from the original locality, the village of Les Baux (or Beaux), near Arles, dep. Bouches-du-Rhône in the south of France, where the material has been for many years extensively mined as an ore of aluminium. It is never found in a crystallized state, but always as earthy, clay-like or concretionary masses, often with a pisolitic structure. In colour it varies from white through yellow and brown to red, depending on the amount and the degree of hydration of the iron present. The specific gravity also varies with the amount of iron; that of the variety known as wocheinite (from near Lake Wochein, near Radmannsdorf, in northern Carniola) is given as 2.55. The numerous chemical analyses, which have mostly been made for technical purposes, show that material known as bauxite varies very widely in composition, the maximum and minimum percentages of each constituent being as follows: alumina (Al2O3) 33.2-76.9; water (H2O) 8.6-31.4; iron oxide (Fe2O3) 0.1-48.8; silica (SiO2) 0.3-37.8; titanic acid (TiO2) up to 4. The material is thus usually very impure, being mixed with clay, quartz-sand and hydroxides of iron in variable amounts, the presence of which may be seen by a microscopical examination. Analyses of purer material often approximate to diaspore or gibbsite in composition, and minute crystalline scales of these minerals have been detected under the microscope.
Bauxite can therefore scarcely be regarded as a simple mineral, but rather as a mixture of gibbsite and diaspore with various impurities; it is in fact strikingly like laterite, both in chemical composition and in microscopical structure. Laterite is admittedly a decomposition-product of igneous or other crystalline rocks, and the same is no doubt also true of bauxite. The deposits in Co. Antrim occur with pisolitic iron ore inter-bedded with the Tertiary basalts, and similar deposits are met with in connexion with the basaltic rocks of the Westerwald in Germany. On the other hand, the more extensive deposits in the south of France (departments Bouches-du-Rhône, Ariège, Hérault, Var) and the southern United States (Georgia, Alabama, Arkansas) are often associated with limestones; in this case the origin of the bauxite has been ascribed to the chemical action of solutions of aluminium sulphate on the limestones.
Bauxite is of value chiefly as a source of metallic aluminium (q.v.); the material is first purified by chemical processes, after which the aluminium hydroxide is reduced in the electric furnace. Bauxite is also largely used in the manufacture of alum and other aluminium salts used in dyeing. Its refractory qualities render it available for the manufacture of fire-bricks and crucibles.
(L. J. S.)
BAVAI, a town of northern France in the department of Nord, 15 m. E.S.E. of Valenciennes by rail. Pop. (1906) 1622. The town carries on the manufacture of iron goods and of fertilizers. Under the name of Bagacum or Bavacum it was the capital of the Nervii and, under the Romans, an important centre of roads, the meeting-place of which was marked by a milestone, destroyed in the 17th century and replaced in the 19th century by a column. Bavai was destroyed during the barbarian invasions and never recovered its old importance. It suffered much during the wars of the 15th, 16th and 17th centuries.
BAVARIA (Ger. Bayern), a kingdom of southern Germany, next to Prussia the largest state of the German empire in area and population. It consists of two distinct and unequal portions. Bavaria proper, and the Palatinate of the Rhine, which lie from 25 to 40 m. W. apart and are separated by the grand-duchies of Baden and Hesse.
Physical Features.—Bavaria proper is bounded on the S. by the Alps, on the N.E., towards Bohemia, by a long range of mountains known as the Böhmerwald, on the N. by the Fichtelgebirge and the Frankenwald, which separate it from the kingdom of Saxony, the principality of Reuss, the duchies of Saxe-Coburg-Gotha and Meiningen and the Prussian province of Hesse-Cassel. The ranges seldom exceed the height of 3000 or 4000 ft.; but the ridges in the south, towards Tirol, frequently attain an elevation of 9000 or 10,000 ft. On the W. Bavaria is bounded by Württemberg, Baden and Hesse-Darmstadt. The country mainly belongs to the basins of the Danube and the Main; by far the greater portion being drained by the former river, which, entering from Swabia as a navigable stream, traverses the entire breadth of the kingdom, with a winding course of 200 m., and receives in its passage the Iller, the Lech, the Isar and the Inn from the south, and the Naab, the Altmühl and the Wörnitz from the north. The Inn is navigable before it enters Bavarian territory, and afterwards receives the Salzach, a large river flowing from Upper Austria. The Isar does not become navigable till it has passed Munich; and the Lech is a stream of a similar size. The Main traverses the northern regions, or Upper and Lower Franconia, with a very winding course and greatly facilitates the trade of the provinces. The district watered by the southern tributaries of the Danube consists for the most part of an extensive plateau, with a mean elevation of 2390 ft. In the mountainous parts of the country there are numerous lakes and in the lower portions considerable stretches of marshy ground. The smaller or western portion, the Palatinate, is bounded on the E. by the Rhine, which divides it from the grand-duchy of Baden, on the S. by Alsace, and on the W. and N. by a lofty range of hills, the Haardtgebirge, which separate it from Lorraine and the Prussian Rhine province.