N I T 
N I T 
N I T 
2/'4 
c.laration, &c. by the clay assigned for that 
purpose, by which omission judgment of 
course is had against him. 
NIMBUS, in antiquity, a circle observed 
on certain medals, or round the head of some 
emperors, answering to the circles of light 
drawn around the images of saints. The 
nimbus is seen on the medals of Maurice, 
Phocas, and others, even of the upper em- 
pire. See also .Meteorology. 
NIPA, a genus of the natural order of 
palms. The male has a spathe ; the corolla 
is six-petalh d. The female has a spathe ; 
corolla none ; drupes angular. 
There is one species, a native of the E. 
Indies. The leaves are used in making 
mats. 
NIPPERS, in a ship, are small ropes 
about a fathom or two long, with a little truck 
at one end, and sometimes only a wale-knot. 
Their use is to help holding off the cable 
horn the main or jeer-capstan, where tiie ca- 
ble is so slimy, so wet, and so great, that they 
cannot strain it, to hold it off with their bare 
h ndsi 
NISI PRIUS, in law, a commission di- 
rected to the judges of assize, empowering 
them to try all questions of fact issuing out 
ol tiie courts at Westminster that are then 
ready for trial by jury. The original of which 
name is this : all causes commenced in the 
courts of West minster-hall are, by course of 
the courts, appointed to be tried on a day 
• fixed in some Easter or Michaelmas term, by 
a jury returned from the county wherein the 
cause of action arises; but with this proviso, 
nisi prius justiciarii ad assisas capiendas vene- 
xint: that is, unless before the clay prefixed 
the judges of assize come into the county in 
question, which they always do in the vaca- 
tion preceding each Easter and Michaelmas 
term, and there try the cause. And then, 
upon the return of tiie verdict given by the 
jury to the court above, the judges there give 
judgment for the party to whom the verdict 
is found. 3 Black. 59. See Assizes. 
NISSOLIA, a genus of the tlecandria or- 
der, in the diadelphia class of plants, and in 
the natural method ranking under the 32d or- 
der, papilionacea?. The calyx is quinque- 
dentate ; the capsule nionospermous, and ter- 
minated by a ligulated wing. There are two 
species* trees of Carthagena. 
NITIDULA, a genus of insects of the 
coleoptera order. The generic character is, 
antennas clavate, the club solid ; shells mar- 
gined ; head prominent ; thorax a little bat- 
tened, margined. There are upwards of 30 
species of this genus. 
NIPRARIA, a genus of the monogynia 
order, in the dodecandria class of plants, and 
in the natural method ranking with those of 
which the order is doubtful. The corolla is 
pen/apetalous, with the petals arched at the 
top; the calyx quinquelid; the stamina 15; 
tiie fruit a monospermous plum. '1 here is 
one species, a shrub of Siberia. 
NITRATS, salts formed by the nitric 
acid. The most important of the nitrats 
have been long known ; and in consequence 
of the singular properties which they possess, 
no class of bodies has excited greater atten- 
tion, or been examined with more unwearied 
industry. See Nitre. They may be dis- 
tinguished by tiie following properties ; 
J. Soluble in water, and capable of crystal- 
lizing by cooling. 2. When heated to red- 
ness, along with combustible bodies, a vio- 
lent combustion and detonation are produced. 
3. Sulphuric acid disengages from them 
fumes, which have the odour of nitric acid. 
4. When heated along with muriatic acid, 
oxymuriatic acid is exhaled. 5. Decom- 
posed by heat, and yield at first oxygen gas. 
The nitrats at present known are 12 in num- 
ber. Tew of them combine with an excess 
of acid or of base, so that there are hardly 
any supernitrats, or subnitrats. 
NITRE, or nit vat of potass. As this salt, 
known also by the name of saltpetre, is pro- 
duced naturally in considerable quantities, 
particularly in Egypt, it is highly probable 
that the antients- were acquainted with it; 
but scarcely any thing certain can be col- 
lected from their writings. If Pliny men- 
tions it at all, he confounds it with soda, 
which was known by the names of nitron and 
nitrum. It is certain, however, that it has 
been known in the East from time immemo- 
rial. Roger Bacon mentions this salt in the 
13th century under the name of nitre. 
No phenomenon has excited the attention 
of chemical philosophers more than the con- 
tinual reproduction of nitre in certain places 
after it had been extracted from them. Pro- 
digious quantities of this salt are necessary 
for the purposes of war ; and as nature has 
not laid up great magazines of it, as she has 
of some other salts, this annual reproduction 
is the only source from which it can be pro- 
cured. It became therefore of the utmost 
consequence, if possible, to discover the 
means which nature employed in forming it, 
in order to enable us to imitate her processes 
by art, or at least to accelerate and facilitate 
them at pleasure. Numerous attempts ac- 
cordingly have been made to explain and to 
imitate these processes. 
Lemery the younger advanced, that all the 
nitre obtained exists previously in animals 
and vegetables ; and that it is formed in these 
substances by the processes of vegetation and 
animalization. But it was soon discovered 
that nitre exists, and is actually formed, in 
many places where no animal nor vegetable 
substance had been decomposed; and con- 
sequently this theory was as untenable as the 
former. So far indeed is it from being true 
that nitre is formed by these processes alone, 
that the quantity of nitre in plants has been 
found to depend entirely on tiie soil in which 
they grow. 
At last, by the numerous experiments of 
several French philosophers, particularly by 
those of Thouvenel, it was discovered that 
nothing else is necessary for the production 
of nitre than a basis of lime, heat, and an 
open but not too free communication with 
dry atmospheric air. When these circum- 
stances combine tiie acid is first formed, and 
afterwards the alkali makes its appearance. 
How the air furnishes materials for this pro- 
due 1 ion is easily explained, now that the 
component parts of the nitric acid are known 
to he oxygen and azote : but how lime con - 
tributes to their union it is not sq easy to see. 
The appearance of the potass is equally ex- 
traordinary. If any thing can give counte- 
nance to the hypothesis that potass is com- 
posed of lime and azote, it is this singular 
fact. 
Nitre is found abundantly on the surface 1 
of the earth in India, South America, ami 
even in some parts of Spain. In Germany 
and France it is obtained by means of artifi- 
cial nitre-beds. These consist of the refuse 
of animal and vegetable bodies undergoing 
putrefaction, mixed with calcareous and 
other earths. It lias been ascertained that 
if oxygen gas is presented to azote at the in- 
stant of its disengagement, nitric acid is form- 
ed. This seems to explain the origin of the 
acid in the-e beds. The azote disengaged 
from these putrefy ing animal substances com- 
bines with the oxygen of the air. The potass 
is probably furnished, partly at least, by the 
vegetables and the soil. 
The mj re is extracted from these beds by 
lixiviating the earthy matters with water. 
This water, when sufficiently impregnated, is 
-evaporated, and a brown-coloured salt ob- 
tained, known by the name of crude nitre. 
It consists of nitre, common salt, nitrat of 
lime, and various other salts. The foreign, 
salts are either separated by repeated crys- 
tallizations, or by washing the salt repeatedly 
with small quantities of water ; for the foreign 
salts being more soluble are taken up first. 
Nitre, when slowly evaporated, is obtain- 
ed in six-sided prisms, terminated by "six- 
sided pyramids ; but for most purposes it is 
preferred in an irregular mass, because in 
that state it contains less water. The pri- 
mitive form of its crystals, according to 
Hauy, is a rectangular octahedron, composed 
of two four-sided pyramids applied base to 
base ; two of the sides are inclined to life 
other pyramid at an angle of 120°; the other 
two at an angle of 1 1 1°. The form of its in- 
tegrant particles is the tetrahedron. The 
six-sided prism is the most common form 
which it assumes. Sometimes, instead of six- 
sided pyramids, these prisms are terminated 
by 18 facets, disposed in three ranges of six, 
as it three truncated pyramids were piled on 
each oilier; sometimes it crystallizes in 
tables. 
The specific gravity of nitre is 1.9309. Its 
taste is sharp, bitterish, and cooling. It is 
very brittle. It is soluble in seven times its 
weight of water at the temperature of 60°, 
and in nearly its own weight of boiling water. 
It is not altered by exposure to the air. 
When the solution of nitre is exposed to a 
boiling heat, part of the salt is evaporated 
along with the water, as Wallerius, lvirwan, 
and Lavoisier, observed successively. When 
exposed to a strong heat it melts, and con- 
geals by cooling into an opaque mass, which 
has been called mineral crystal. Whenever 
it melts it begins to disengage oxygen ; and 
by keeping it in a red heat about the third of 
its weight of that gas may be obtained : to- 
wards the end of the process azotic gas is dis- 
engaged. If the heat is continued long 
enough the salt is completely decomposed, 
and pure potass remains behind. 
It detonates more violently with combus- 
tible bodies than any of the other nitrats. 
When mixed with one-third part of its weight 
of charcoal, and thrown intoa red-hot crucible, 
or when charcoal is thrown into red-hot nitre, 
detonation takes place, and one of the most 
brilliant combustions that can be exhibited. 
The residuum is carbonat of potass, ft was 
formerly called nitre fixed by charcoal. A 
still more violent detonation is produced by- 
using phosphorus instead uf charcoal, Whe* 
