N I T 
N I T 
N I T 
a mixture of nitre and phosphorus is struck 
smartly with a hot hammer a very violent de- 
tonation is produced. 
Nitre oxidizes all the metals at a red heat, 
even gold and platinum. 
Nitre, according to Bergman, is composed 
®f 
3 1 acid 
61 potass 
8 water* 
100 
According to the latest experiments of Kir- 
i wan, after being dried in the temperature of 
70°, it is composed of 
44.0 acid 
51-8 potass 
4.2 water. 
100.0 
Nitre is decomposed by the following salts: 
1. Sulphats of soda, ammonia, magnesia, 
| alumina. 
2. Muriat and aectat of barytes. 
One of the most important compounds 
? formed by means of nitre is gunpowder, 
I v* fell has completely changed the modern 
art of war. See Gunpowder. 
NITRIC ACID seems to have been first 
obtained in a separate state by Raymond 
Lully, who was born at Majorca in 1235. 
* lle procured it by distilling a mixture of ni- 
tre and clay. It was afterwards denominated 
aquafortis, and spirit of nitre. The name 
nitric acid was first given it in 1787 by the 
French chemists ; it was immediately before 
» called nitrous acid. 
1. It is generally obtained in large manu- 
factories by distilling a mixture of nitre and 
clay ; but the acid procured by this process 
is weak and impure. Chemists generally 
I prepare it by distilling three parts of nitre 
| and one of sulphuric acid in a glass retort. 
' The neck of the retort must be luted into a 
| receiver, from which there passes a glass 
tube into a bottle- with two mouths, contain- 
| ing a little water, and furnished with a tube. 
I of safety ; which is a tube open at its upper 
i end, and having its lower end plunged in wa- 
ter. The water prevents any coiVnnunication 
| between the external air and the inside of 
the apparatus. If a vacuum happens to be 
formed within the vessels, the external air 
; readies down through the tube, and prevents 
any injury to the vessels. On the other 
band, if air is generated in the vessels It 
| forces the water up the tube, the height of 
I which becomes thus the measure of the elas- 
I ticity of the air in the vessels. By this con- 
| trivance the apparatus is in no danger of be- 
I ing broken, which otherwise might happen. 
From the other mouth of this bottle there 
I passes a tube into a pneumatic apparatus, to 
collect the gas which is evolved during the 
process. The retort is to be heated gradually 
almost to redness. The nitric acid comes 
I over, and is condensed in the receiver ; while 
I the common air of the vessels, and a quantity 
| of oxygen gas which is evolved, especially to- 
I wards the end of the process, passes into the 
pneumatic apparatus, and the water in the 
bottles is impregnated with some acid which 
is not condensed in the receiver. 
The acid thus obtained is of a yellow co- 
lour, and almost always contains muriatic and 
sometimes sulphurous acid. These may be 
removed by distilling it over again with a 
moderate heat, and changing the receiver 
after the first portion, which contains all the 
foreign acids, has passed. It still contains a 
quantity of nitrous gas, to which it owes its 
colour and the red fumes which it exhales. 
This gas may also be expelled by the appli- 
cation of heat. Pure nitric acid remains be- 
hind, transparent and colourless, like water. 
When newly prepared in this manner it is 
a liquid as transparent and colourless as wa- 
ter; but the affinity between its component 
parts is so weak, that the action of light is 
sufficient to drive off a part of its oxygen in 
the form of gas ; and thus, by converting it 
partly into nitrous gas, to make it assume a 
yellow colour, its taste is exceedingly acid 
and peculiar. It is very corrosive, and 
tinges the skin of a yellow colour, which does 
not disappear till the epidermis comes off. It 
is constantly emitting white fumes which have 
an acrid disagreeable odour. 
It has a strong affinity for water, and has 
never yet been obtained except mixed with 
that liquid. When concentrated it attracts 
moisture from the atmosphere, but not so 
powerfully as sulphuric acid. It also pro- 
duces heat when mixed with water, owing 
evidently to the concentration of the water. 
The specific gravity of the strongest nitric 
acid that can be procured is 1.583 ; but at 
the temperature of 60°, Mr. Kirwan could 
not procure it stronger than 1.5543. 
As this liquid acid is a compound of two 
ingredients, namely, pure nitric acid and wa- 
ter, it becomes an object of the greatest 
consequence to ascertain the proportion of 
each of these parts. This problem lias lately 
occupied the attention of Mr. Kirwan, who 
has endeavoured to solve it in the following 
manner : 
He dried a quantity of crystallized carbo- 
nat of soda in a red heat, and dissolved it in 
water, in such a proportion that 367 grains 
of the solution contained 50.05 of alkali. He 
saturated 367 grains of this solution with 147 
grains of nitric acid, the specific gravity of 
which was 1.2754; and which he ascertained 
to contain 45.7 per cent, of acid, of the spe- 
cific gravity 1.5543, chosen by him as a 
standard. The carbonic acid driven off 
amounted to ]4 grains. On adding 939 
grains of water the specific gravity of the so- 
lution, at the temperature of 58.5°, was 
1.0401. . By comparing this with a solution 
of nitrat of soda, of the same density, he 
found that the salt contained in it amounted 
to of the whole. There was an excess 
16.901 
of acid of about two grains. The weight of the 
whole was 1439 grains : the quantity of salt 
] 439 
consequently was = 85.142 grams. The 
quantity of alkali was 50.05 — 14— 36.05. The 
quantity of standard acid employed was 66.7. 
The whole therefore amounted to 102.75 
grains; but as only 85.142 grains entered 
into the composition of the salt, the remain- 
ing 17.608 must have been pure water mixed 
with the nitric acid. But it 66.7 of standard 
acid contain 17.608 of water, 100 parts of 
the same acid must contain 26.38. One hun- 
dred parts of standard nitric -acid, therefore, 
are composed of 73.62 parts of pure nitric acid 
and 26.38 of water. 
Mr. Davy considers as- pure add the per- 
M m 2 
275 
manently elastic vapour or gas formed by sa- 
turating nitrous gas with oxygen gas. This 
gas is of a pale-yellow colour, and a specific 
gravity 2.44 times that of air. It is not pure 
acid, containing undoubtedly a portion of ni- 
trous gas. The following table exhibits the 
proportion of this acid contained in nitric 
acid of different densities, according to the 
experiments of that ingenious chemist : 
100 Parts 
Nitric Acid, 
of Sp. Gr. 
True Acid. 
Water. 
1.5040 
91.55 
8.45 
1.4475 
80.39 
19.61 
1.4285 
71.65 
28.35 
1.3906 
62.96 
37.04 
1.3551 
56.88 
43.12 
1.3186 
52.03 
47.97 
1.3042 
49.04 
50.96 
1.2831 
46.03 
53.97 
1.2090 
45.27 
54.73 
When nitric acid is exposed to the action 
of heat it boils at the temperature of 248, 
and evaporates completely without altera- 
tion; but when made to pass through a red- 
hot porcelain tube it is decomposed, and. 
converted into oxygen and azotic gas. When 
cooled clown to — 66 it begins to congeal ; 
and when agitated it is converted into a mass 
of the consistence of butter. 
Oxygen gas has no action whatever on ni- 
tric acid ; but all* the simple combustibles 
decompose it, unless we are to except the dia- 
mond. When poured upon sulphur or phos- 
phorus at a high temperature it sets them on 
fire; but at a moderate temperature it con- 
verts them slowly into acids, while nitrous 
gas is exhaled. It inflames charcoal also at 
a high temperature ; and even at the common 
temperature, provided the charcoal is perfect- 
ly dry and minutely divided. Hydrogen gas 
produces no change on it at the temperature 
of the atmosphere ; but when passed along 
with it through a red-hot porcelain tube it 
detonates with great violence ; water is form- 
ed, and azotic gas evolved. 
When this acid is poured upon oils it se(s 
them on lire. This is occasioned by a de- 
composition both of the acid and oil. The 
oxygen of the acid combines with the carbon 
and with the hydrogen of the oils, and at the 
same time lets go a quantity of caloric. 
Hence we see that the oxygen which enters 
into the composition of the nitric acid still 
contains a great deal of caloric ; a fact which 
is confirmed by a great number of other phe- 
nomena. The combustion of oils by this 
acid was first taken notice of by Borricbius 
and Slave; but it is probable that Homberg 
communicated it to blare. In order to set 
fire to the fixed oils it must be mixed with 
some sulphuric aqid ; the reason of which 
seems to be, that these oils contain water, 
which must be previously removed. The 
sulphuric acid combines with this water, and 
allows the nitric acid, or rather the oil and 
nitric acid together, to act. The drying oils 
do not require any sulphuric acid : they have 
been boiled, and consequently deprived of all 
moisture. 
Azote has no action on nitric acid ; but 
muriatic acid decomposes it by combining 
