1911 Encyclopædia Britannica/Bole

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Bole (Gr. βῶλος, “a clod of earth”), a clay-like substance of red, brown or yellow colour, consisting essentially of hydrous aluminium silicate, with more or less iron. Most bole differs from ordinary clay in not being plastic, but in dropping to pieces when placed in water, thus behaving rather like fuller’s-earth. Bole was formerly in great repute medicinally, the most famous kind being the Lemnian Earth (γῆ Δήμνια), from the Isle of Lemnos in the Greek Archipelago. The earth was dug with much ceremony only once a year, and having been mixed with goats’ blood was made into little cakes or balls, which were stamped by the priests, whence they became known as Terra sigillata (“sealed earth”). Large quantities of bole occur as red partings between the successive lava flows of the Tertiary volcanic series in the north of Ireland and the west of Scotland. Here it seems to have resulted from the decomposition of the basalt and kindred rocks by meteoric agencies, during periods of volcanic repose. In Antrim the bole is associated with lithomarge, bauxite and pisolitic iron-ore. Bole occurs in like manner between the great sheets of the Deccan traps in India; and a similar substance is also found interbedded with some of the doleritic lavas of Etna.

In the sense of stem or trunk of a tree, “bole” is from the O. Norwegian bolr, cf. Ger. Bohle, plank. It is probably connected with the large number of words, such as “boll,” “ball,” “bowl,” &c., which stand for a round object.