BAR 
chemists were confirmed by Bergman, who 
gave the earth the name of terra ponderosa. 
Morveau gave it the name of barote, and 
Kirwan of barytes ; Which last was approv- 
ed by Bergman, and is now universally 
adopted. Barytes may be obtained in a 
state of purity, by the calcination of its 
carbonate or nitrate. It exhibits, when 
pure, the following properties. 1. Barytes, 
in a pure form, has a sharp caustic taste, 
changes vegetable blue colours to green ; 
and serves as the intermedium between oil 
and water: in these respects it bears a 
strong resemblance to alk alis. % When ex- 
posed to the flame of the blow-pipe on char- 
coal, it melts; boils violently; and forms 
small globules, which sink into the char- 
coal. If perfectly free from water, how- 
ever, it is infusible. 3. If a small quantity 
Ot water be added to recently prepared 
barytes, it is absorbed with great rapidity; 
prodigious heat is excited ; and the water 
is completely solidified, a sort of hard ce- 
ment being obtained. A little more water 
converts this mass into a light bulky pow- 
der; and when completely covered with 
water, the barytes is dissolved. Boiling 
water should be employed for this purpose, 
unless sufficient temperature has been pro- 
duced by the sudden addition of the whole 
quantity necessary for solution. 4. When 
the solution, prepared with boiling water, 
is allow ed to cool slowly, it shoots into re- 
gular crystals. These have the form of 
flattened hexagonal prisms, having two 
broad sides, with two intervening narrow 
ones ; and terminated at each end by a 
quadrangular pyramid. 5 , The crystals are 
so soluble as to be taken up when heated, 
merely by their own water of crystalliza- 
tion. When exposed to a stronger heat, 
they swell, foam, and leave a dry white 
powder, amounting to about 4 7 parts from 
100 of the crystals. This again combines 
with water with great heat and violence. 
At 60° of Fahrenheit, an ounce-measure of 
water dissolves only 25 grains of the crys- 
tals, i. e. they require for solution 171 times 
their weight of water. Exposed to the at- 
mosphere, they effloresce, and become pul- 
verulent. 6 , When added to spirit of wine, 
and heated in a spoon over a lamp, they 
communicate a yellowish colour to its 
flame. 7. The specific grayity of this earth, 
according to Foureroy, is 4, but Hassenfratz 
states it at only 2.374, The former ac- 
count, however, is the more probable, All 
its combinations have considerable specific 
grayity ; and hence its name is derived, viz. 
BAS 
from the Greek word fiaeve, signifying 
heavy. 8 . Barytes does not unite with any 
of the alkalis. 
BASALT, in mineralogy, occurs massive, 
in blunt and rolled pieces, and sometimes 
vesicular: its common colour is greyish 
black, of various degrees of intensity ; from 
this it passes into ash-grey; sometimes to 
brown, and even in some varieties to raven 
black. It is dull internally, and the frac- 
ture is commonly coarse-grained and un- 
even. It occurs almost always in distinct 
concretions, which are usually columnar, 
and from a few inches to several fathoms, 
and even to upwards of 100 feet in length. 
They are sometimes straight, sometimes 
bent, and either parallel or diverging. In 
mountains these concretions are collected 
into larger groupes, of which many together 
form a hill or a mountain. Sometimes the 
columns are articulated, and the joints have 
convex and concave faces. The specific 
gravity is by Bergman put at 3.0: by 
Brisson at 2.86 : and by Kirwan at 2.98. 
Before the blow-pipe it easily melts without 
addition into an opaque black glass. By 
analysis the constituent parts have been 
brought out differently by different che- 
mists, but according to Klaproth they are 
as follow : 
Silica 44.50 
Alumina 16.75 
Oxide of iron 20.00 
Lime 9.50 
Magnesia 0.25 
Oxide of manganese 0.12 
Soda 2.60 
Water 2.00 
97~.62 
It is found in vast mountainous beds, in 
most parts of the world, and almost always 
accompanies coal. The island of Staffa, on 
the western coast of Scotland, is entirely 
composed of basaltic pillars: the Giants 
Cause-way, on the coast of Antrin, in Ire- 
land, is a huge pavement of straight pillars, 
running to an unknown distance in the sea : 
the promontory of Fair-head, a little further 
to the north, exhibits a continued range, 
about a mile long, of columns 250 feet in 
height, and from 10 to 20 in diameter, 
being the largest yet known. 
Basalt is employed as a building stone, 
and touch stone ; as a flux for certain ores 
of iron ; in glass manufactures ; in making 
the common green glass. The vesicular 
varieties are employed for millstones, 
