In its various forms, bitumen is one of the most widely distributed of substances. It occurs, though sometimes only in small quantity, in almost every part of the globe, and throughout the whole range of geological strata, from the Laurentian rocks to the most recent members of the Quaternary period. Although the gaseous and liquid forms of bitumen may be regarded as having been formed in the strata in which they are found or as having been received into such strata shortly after formation, the semi-solid and solid varieties may be considered to have been produced by the oxidation and evaporation of liquid petroleum escaping from underlying or better preserved deposits into other strata, or into fissures where atmospheric action and loss of the more volatile constituents can take place. It should, however, be stated that there is some difference of opinion as to the precise manner of production of some of the solid forms of bitumen, and especially of ozokerite. (B. R.)
BITURIGES, a Celtic people, according to Livy (v. 34) the most powerful in Gaul in the time of Tarquinius Priscus. At some period unknown they split up into two branches--Bituriges Cubi and Bituriges Vivisci. The name is supposed to mean either "rulers of the world" or "perpetual kings."
The Bituriges Cubi, called simply Bituriges by Caesar, in whose time they acknowledged the supremacy of the Aedui, inhabited the modern diocese of Bourges, including the departments of Cher and Indre, and partly that of Allier. Their chief towns were Avaricum (Bourges), Argentomagus (Argenton-sur-Creuse), Neriomagus (Néris-les-Bains), Noviodunum (perhaps Villate). At the time of the rebellion of Vercingetoix (52 B.C.), Avaricum, after a desperate resistance, was taken by assault, and the inhabitants put to the sword. In the following year, the Bituriges submitted to Caesar, and under Augustus they were incorporated (in 28 B.C.) in Aquitania. Pliny (_Nat. Hist._ iv. 109) speaks of them as _liberi_, which points to their enjoying a certain amount of independence under Roman government. The district contained a number of iron works, and Caesar says they were skilled in driving galleries and mining operations.
The Biturgies Vivisci occupied the strip of land between the sea and the left bank of the Garonne, comprising the greater part of the modern department of Gironde. Their capital was Burdigala (Bordeaux), even then a place of considerable importance and a wine-growing centre. Like the Cubi, they also are called _liberi_ by Pliny.