as I.

BOROLANITE, one of the most remarkable rocks of the British Isles, found
on the shores of Loch Borolan in Sutherlandshire, after which it has
been named. In this locality there is a considerable area of granite
rich in red alkali felspar, and passing, by diminution in the amount of
its quartz, into quartz-syenites (nordmarkites) and syenites. At the
margins of the outcrop patches of nepheline-syenite occur; usually the
nepheline is decomposed, but occasionally it is well-preserved; the
other ingredients of the rock are brown garnet (melanite) and aegirine.
The abundance of melanite is very unusual in igneous rocks, though some
syenites, leucitophyres, and aegirine-felsites resemble borolanite in
this respect. In places the nepheline-syenite assumes the form of a dark
rock with large rounded white spots. These last consist of an
intermixture of nepheline or sodalite and alkali-felspar. From the
analogy of certain leucite-syenites which are known in Arkansas, it is
very probable that these spots represent original leucites which have
been changed into aggregates of the above-named minerals. They resemble
leucite in their shape, but have not yet been proved to have its
crystalline outlines. The "pseudo-leucites," as they have been called,
measure one-quarter to three-quarters of an inch across. The dark matrix
consists of biotite, aegirine-augite and melanite. Connected with the
borolanite there are other types of nepheline-syenite and pegmatite. In
Finland, melanite-bearing nepheline rocks have been found and described
as Ijolite, but the only other locality for melanite-leucite-syenite is
Magnet Cove in Arkansas. (J. S. F.)

BORON (symbol B, atomic weight 11), one of the non-metallic elements,
occurring in nature in the form of boracic (boric) acid, and in various
borates such as borax, tincal, boronatrocalcite and boracite. It was
isolated by J. Gay Lussac and L. Thenard in 1808 by heating boron
trioxide with potassium, in an iron tube. It was also isolated at about
the same time by Sir H. Davy, from boracic acid. It may be obtained as a
dark brown amorphous powder by placing a mixture of 10 parts of the
roughly powdered oxide with 6 parts of metallic sodium in a red-hot
crucible, and covering the mixture with a layer of well-dried common
salt. After the vigorous reaction has ceased and all the sodium has been
used up, the mass is thrown into dilute hydrochloric acid, when the
soluble sodium salt