368 
BASALT. » 
cine, in the treatment of scrofulous diseases, 
though, from its poisonous nature, great caution 
is requisite in its administration. 
BASALT. A rock of igneous origin, and very 
extensive occurrence. The colour of this rock is 
dark greyish black, or brownish grey. It is found 
in large shapeless masses, or in columnar prisms, 
with from three to nine faces. These columns are 
of all sizes, from a few inches to several feet in 
diameter, and sometimes four hundred feet in 
height. They are composed of joints, or blocks 
of the same angular shapes, resting one upon 
another. The texture of basalt is fine grained, 
or compact, and it consists of an intimate mixture 
of a number of other minerals, among which may 
be distinguished augite or hornblende, labrador- 
ite or nephelin, magnetic and titaniferous iron 
ore, olivine and one or more zeolites, all of which 
often occur separated in the basalt. C. Gmelin 
was the first to show that basalt consists of 
two portions, one of which is decomposable by 
acids, the other not. All later chemical investi- 
gations have been based on this fact, but without 
yet being able to separate or distinguish, with 
sufficient accuracy, the different minerals of 
which it is composed; for, if a dilute acid be 
employed, olivine and magnetic iron ore are only 
imperfectly decomposed, while, by a stronger 
acid, portions of augite and labradorite are, at 
the same time, also attacked. From the same 
reason, it is also difficult to determine the par- 
ticular species of zeolite which it contains. Basalt 
is distinguished from lava by its content of water, 
which averages about 2'5 per cent., and of which 
lava only contains hygroscopical portions. 
BASE, or Basis. Any substance capable of 
combining with acids, and neutralizing more or 
less their acid properties, and thus forming salts 
with them. Every true salt, therefore, consists 
of an acid and a base, or, in electro-chemical 
language, of an electro-negative and electro-posi- 
tive ingredient: see article Saurs. The alkalies 
possess, therefore, in the highest degree, the 
character of bases, and the latter word is only a 
wider extension of the term alkali, from the sup- 
position that the alkaline ingredient of a salt 
constituted its most important and characteristic 
part, or the basis of it. For the same reason, the 
term basis is often, but less frequently, extended 
to the electro-positive element of the alkalies 
themselves, or of any other binary compound, in 
which latter sense it becomes synonymous with 
radical; thus, potassium is said to be the metallic 
basis or radical of potassa (oxide of potassium) 
and of chloride of potassium. As the term salt 
was extended beyond oxysalts to other ternary 
compounds, such as sulpho-salts, chloro-salts, &c., 
it has also become necessary to extend the term 
base to the electro-positive ingredient in these 
salts, and we thus distinguish between oxy-bases, 
sulpho-bases, chloro-bases, &c. Thus, oxide of 
copper is an oxy-base, because it combines with 
oxacids, such as arsenic acid, forming an oxysalt, 
BASIL. 
the arseniate, or more correctly, the oxy-arseni- 
ate of copper; while the sulphuret of copper is a 
sulpho-base, combining with sulph-acids as, for 
instance, with sulpharsenic acid to a sulpho-salt, 
the sulpharseniate of copper. Under the term 
oxybases, or simply bases, as they often are called, 
where no reference is made to other kinds of 
bases (such as sulpho-bases, &c.), are, therefore, 
comprehended the alkalies, the alkaline earths, 
the earths, and generally all those oxides which 
are capable of combining with, and more or less 
neutralizing oxacids, and forming salts with them, 
such as the oxides of iron, copper, &c., for which 
we refer to the different metals. To this class of 
bases belong also a class of organic, nitrogenous 
substances mostly obtained from plants, or arti- 
ficially produced, which have all the properties of 
the metallic or inorganic bases, and are capable of 
replacing them in their combinations. These are 
termed vegetable alkalies or alkaloids: see ALKALOID. 
But their character as oxides or oxybases is even 
more doubtful than that of ammonia (or oxide of 
ammonium), with which they seem to have an 
analogous constitution, while their basic proper- 
ties, at the same time, seem dependent on the 
amount of nitrogen which they contain. The 
oxides of ethyl (ether) and methyl form another 
class of organic bases, which may be combined 
with acids and neutralize their acid properties, 
and are therefore also called organic bases, but | 
their combination with the acids differ consider- 
ably in their nature from the ordinary inorganic 
salts by not allowing their acids or bases to be 
replaced or exchanged, with the same facility, by 
single or double affinity for other bases or acids. 
BASELLA. A genus of tender twining plants, 
of the goosefoot tribe. Five species, the white, 
the red, the black, the shining, and the heart- 
leaved, are cultivated for various purposes in 
India and China; and two species are grown as 
ornamental stove plants in Great Britain. The 
kind longest known in Britain has a strong, 
thick, succulent stem, and deep purple-coloured 
leaves; and is popularly called climbing night- 
shade or Malabar night-shade. The juice of the 
berries yields a beautiful but fugitive dye. 
BASIL,—hbotanically Ocymum. A genus of 
plants, of the lip-flowered tribe. The common 
basil, usually called sweet basil, Ocymum basilr- 
cum, is a tender, aromatic herb, used for soups, 
salads, and other culinary purposes, and particu- 
larly noted for imparting to mock turtle soups 
their peculiar grateful flavour. It is an annual, 
and a native of India, and was introduced to 
Great Britain about the middle of the 16th cen- 
tury. Its stem is branching, hairy, quadrangu- 
lar, and about a foot in height; its branches are 
hairy and quadrangular, and are produced in 
mutually opposite pairs, all the way up the stem ; 
its leaves are oval, spear-shaped, dentated, and 
ending in acute points; and the whole plant has 
a strong aromatic flavour similar to that of cloves. 
Its principal varieties are common basil, with 
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