BAG 
B A C 
BAG 
192 
acid, therefore, is composed of azote and 
oxygen: and these two substances are ca- 
pable of combining; or, which is the same 
thing, azotic gas is capable of combustion in 
the temperature produced by electricity, 
which we know to be high. The combina- 
tion of azotic gas with oxygen, and the na- 
ture of the product, were discovered by Mr. 
Cavendish, and communicated to the Royal 
Society on the 2d of June 1785. 
When sulphur is melted in azotic gas, part 
of it is dissolved, and sulphurated azotic gas 
formed. This gas lias a fetid odour. Its 
properties are still unknown. 
Phosphorus plunged into azotic gas is dis- 
solved in a small proportion. Its bulk is en- 
creased about l-40lh, and phosphureted azotic 
gas is the result. When tin's gas is mixed 
■with oxygen gas, it becomes luminous, in 
consequence of the combustion of the dis- 
solved phosphorus. The combustion is most 
rapid when bubbles of phosphureted azotic 
gas are let up into a jar full of oxygen gas. 
When phosphureted oxygen gas and phos- 
phureted azotic gas are mixed together, no 
light is produced, even at the temperature 
of 82°. 
Azotic gas dissolves also a little carbon ; 
for azotic gas obtained from animal sub- 
stances, by Berthollet’s process, when con- 
lined long in jars, deposits on the sides of 
them a black matter, which has the proper- 
ties of charcoal. 
\Y hen mixed with hydrogen gas, it under- 
goes no change. It may, however, be com- 
bined with hydrogen, and the compound 
formed is known by the name of ammonia or 
volatile alkali. 
The affinities of azote are still unknown. 
It has never yet been decompounded; and 
must therefore, in the present state of our 
knowledge, be considered as a simple sub- 
stance. See Air, page 3 1 . 
AZURE, in heraldry, the blue colour in 
the arms of any person below the rank of a 
baron. In the escutcheon of a nobleman, it 
is called saphire ; and in that of a sovereign 
prince, Jupiter. In engraving, this colour iai 
expressed by lines or strokes drawn hori| 
zontally. 
AZYGOS, in anatomy, a vein rising within 
the thorax on the right side, having no fellow! 
on the left; whence it is called azygos, of 
vena sine pari. 
AZYMJTES, in church-history, Christians 
who administer the eueharist with unleavened 
bread. 
AZYMOUS, something unfermented ; as 
bread, &c. made without leaven. This term- 
lias occasioned frequent disputes, and, at 
length, a rupture between the Latin and the; 
Greek churches; the former of which main- 
tain, that the bread in the mass ought to be' 
azymous, unleavened, in imitation of tin 
paschal bread of the Jews, and of our Saviour, 
who instituted the sacrament on the day of 
the passover. The latter as strenuously main- 
tain the contrary from tradition, and the 
common usage ot the church. 
B the second letter of the alphabet, is used 
2 as an abbreviation: in music, B stands for 
the tone above A: B also stands for bass, 
and B. C. for basso continuo, or thorough 
bass. As a numeral, B was used by the 
Greeks and Hebrews, to denote 2 : but 
among the Romans, for 300, and with a dash 
over it (thus 13) for 3000. The same people 
likewise used B. for Brutus, B. F. forbonum 
factum. B, in the old chemical alphabet, signi- 
fies Mercury : B. A. stands for bachelor of 
arts; B. L. for bachelor of laws; and B. D. for 
bachelor of divinity. 
BABOON, in zoology. See Simia. 
BABYLON1CA, texta, a rich sort of weav- 
ings, or hangings, so denominated from the 
city of Babylon, where the practice of inter- 
weaving divers colours in their hangings was 
first invented. 
BAG A, in botany. See Berry. 
BACCHd?., in antiquity, priestesses of the 
god Bacchus. They were likewise called 
mamades, on account of the frantic ceremo- 
nies vised in their feasts ; as also thyades, 
which signifies impetuous, or furious. 
BACCHANALIA, feasts celebrated in 
honour of Bacchus by the antient Greeks 
and Romans ; of which the two most re- 
markable were called the greater and lesser. 
The latter were held in the open fields about 
autumn; but the greater, called dionysia, 
were celebrated in the city in spring time. 
BACCIIARIS, in botany, ploughman's 
spikenard, a genus of the polygamia super- 
fiua order, belonging to the syngenesia class 
of plants; and in the natural method ranking 
under the 49th order, con, posits discoides. 
The characters are ; it has a naked recep- 
tacle, and hairy pappus ; with a cylindrical 
imbricated calyx, and feminine ilorets mixed 
with the hermaphrodite ones. There are 9 
species, all natives of warm climates; of 
which the two following chiefly merit notice. 
1. Baccharis halimifolia,’ or Virginia 
groundsel-tree, a native of Virginia and other 
parts of North America. It grows about 7 
or 8 feet high, with a crooked shrubby 
stem; and flowers in October. The flowers 
B. 
are white, and not very beautiful ; but the 
leaves continuing green, has occasioned this 
shrub to be admitted into many curious gar- 
dens. It may be propagated by cuttings ; 
and will live very well in the open air, though 
severe frost will sometimes destroy it. 
2. Baccharis ivaefolia, or African tree- 
groundsel, a native of the Cape of Good 
Hope, as well as of Peru and other warm 
parts of America. It grows to the height of 
5 or 6 feet ; and though there is little beauty 
in the flower, has been long admitted into the 
gardens of the curious. It is pretty hardy, 
and will live abroad in moderate winters in 
England; but is usually kept in green-houses, 
and placed abroad only in summer. It may 
be propagated either by cuttings or by seeds, 
which ripen well in this country. 
BACCHIUS, in antient poetry, a kind of 
foot composed of a short syllable and two 
long ones. 
BACILLARIA, in natural history, a genus 
of vermes infusoria:, of which only a single 
species is described. The body consists of 
straw-like cylinders, placed parallel to each 
other, and frequently changes its direction 
and arrangement. 
BACK, in brewing, a large flat kind of tub 
or vessel, in which the wort is put for cooling. 
The ingredients of beer pass through three 
kinds of vessels; they are mashed in one, 
worked in another, and cooled in a third. 
See Brewing. 
Back the sails, is to put them in a situation 
that will occasion the ship to retreat or move 
astern. 
Back, in the manege. To back a horse, 
or mount a horse a dos in French, is to 
mount him bare-backed, or without a saddle. 
Back-gammon, an ingenious game play- 
ed with dice and tables, to be learned only 
bv observation and practice . However, the 
following rules concerning it cannot fail to 
be acceptable to our reaclers. In the first 
place, the men, which are 30 in number, 
being equally divided between the two game- 
sters, are placed thus, viz. two on the ace 
point, five on the side of your left-ha 
three on the cinque, and live on 
point of your right-hand table, which are an^ 
swered on the like points by your adversary* 
men : or they may be disposed thus, viz. twi* 
on the ace point, five on the double sice or 
sice-cinque point, three on the cinque point 
in your own tables, and five on the sice point 
at home; which are to be answered by your 
adversary. The men being thus disposed, 
be sure to make good your trey and act 
points; hit boldly, and come away as fast as 
you can. When you come to bearing, have 
a care of making when you need not ; and 
doublets now will stand you most in stead, 
If both bear together, he that is first ofi^ 
w ithout doublets, wins one ; if both bear, anc 
one goes off’ with doublets, he wins two. I: 
your table be clear before your a iversaryl 
men are come in, that is a back-gammon, 
which is three ; but if you thus go on wit! 
doublets, it is four. 
The great dexterity of this game is to be 
forward, if possible, upon safe terms ; and sot 
to point the men, that it shall not be possible 
•for the adversary to pass, though you have 
entered your men, till you give him liberty, 
after having got two to one of the advantage 
of the game. 
Back-staff, in the sea language, an in- 
strument to take the sun’s altitude. It con- 
sists of two concentric arches, the greater o 
which is divided into 30 degrees, and every 
degree into 5 minutes, by means of diagona 
lines; and the lesser into 60 degrees. 4 here 
are likewise 3 vanes belonging to it: tha 
upon the arch of 30 degrees, being callej 
the sight vane ; that upon the arch of 60 de 
grees,tthe shade vane ; and the other, in the 
centre of the arches, the horizon vane. 
To find the sun’s altitude by this instruj 
ment, fix the shade vane on the 60 degreed 
arch, at about 15 or 20 degrees less than the 
complement of the altitude; and turning 
your back towards the sun, move thg 
sight vane up and down till the sun’s image 
fall on the horizon vane, and at the same 
d table, 
the tcej 
