| 302 AZAROLE. AZOTE. 
peat and loam or sandy peat.—Hortus Britanni- 
cus.—Gardener’s Magazine.—Botanical Register.— 
Miller.—Marshall—Mawe.—The Botanic Garden. 
AZAROLE,—botanically Crategus Azarolus. 
A tall, ornamental, deciduous shrub, of the haw- 
thorn genus. It isa native of Italy and the south 
of France, and was introduced to Great Britain 
in 1640. It usually grows to the height of about 
15 feet, and blooms in May and June. Its leaves 
are large, nearly trifid, serrated, and obtuse; and 
its flowers are large, and, in the different varie- 
ties, are succeeded by fruit of different size, shape, 
and flavour.—The scarlet-fruited species of haw- 
thorn, Crategus coccinea, is also generally known 
under the name of Virginian azarole. It is a 
native of North America, and was introduced to 
Britain in 1683. It grows to the height of nearly 
20 feet; its stem is robust, and covered with a 
light-coloured bark ; its branches ramify and ex- 
tend in an irregular and rambling manner, and 
are of a dark brown colour, and armed witha 
few long, sharp thorns; its leaves are ovate- 
spear-shaped, smooth, serrated, and of a thick 
| consistence, and often remain on the tree during 
the greater part of winter; its flowers appear in 
May, and are individually large, but grow in 
such small groups as to form rather small umbels ; 
and its fruit is large and of a dark red colour, 
and ripens late in autumn.—The species of aza- 
role are propagated from seeds; and the varie- 
ties, by budding upon stocks of the white thorn. 
AZEDARACH. See Bean-TReEs. 
AZOTE, or Nitrogen. A gas, the largest con- 
stituent of the atmospheric air, and one of the 
| most important elementary substances in the 
world. It was discovered, as a distinct substance, 
in 1772, by Dr. Rutherford of Edinburgh, and as- 
certained to be a constituent of the atmosphere, 
about 1775, by Lavoisier and Scheele. Its name 
azote means ‘ without life,’ and was given to it 
by Lavoisier on account of its total want of adap- 
tation to sustain animal life; and its name nitro- 
gen means ‘ the generator of nitre, and was given 
to it on account of its being an essential element 
of nitric acid and all nitrate salts. It does not 
naturally exist in a separate condition, and is 
usually obtained, in experimental chemistry, by 
an intricate process of extraction from the oxy- 
gen and the other elements of the atmosphere. 
It cannot, without great difficulty and much ela- 
boration of chemical process, be obtained in a 
pure condition; and, in consequence, it is liable 
to be blamed for bad odours and even worse pro- 
perties, which really belong to partial combina- 
tions with it of some other elements. When 
quite pure, it is the most seemingly negative of 
all the gases, totally destitute of colour, taste, 
or smell, quite incapable of acting upon blue 
vegetable colours, and distinguished from other 
gases more by negative characters than by any 
striking or very active property. It cannot sup- 
port combustion, but extinguishes the flame of 
all burning bodies which are dipped into it; and 
it cannot support animal respiration, but extin- 
guishes the life of all animals which are immersed 
in it; yet it operates upon both flame and life 
rather by negation than by action,—rather by 
the want of intermixed or accompanying oxy- 
gen, than by any deleterious or even positive 
influence of its own. Hence an animal which 
dies by immersion in it exhibits, upon ost 
mortem examination, no traces of injurious 
action upon either the lungs or the general 
functionary system. 
azote is estimated by Dulong and Berzelius at 
0:976, by Dr. Thomson at 0:9722, and by Dr. Tur- 
ner at 0:9727. A question has, for a considerable 
number of years, perplexed and partly divided 
chemists, as to whether azote, though usually 
classed as a simple substance, is not really a com- 
pound ; and this question has repeatedly been put 
to the test of ingenious experiment, and answered 
in the affirmative, yet must still be regarded as 
unsolved. 
So very seemingly inactive is azote, that, 
though constituting about four-fifths of the 
whole atmosphere, it has been supposed by some 
chemists to serve merely as a diluent or men- 
struum of oxygen, weakening the strength or | 
softening the energy of that mighty principle of 
combustion, acidification, and respirational ac- | 
tion, and preventing the oxygen from exerting 
such a stimulating effect upon the animal func- 
tions as should speedily wear them to extinction. | 
Even some adepts in organic chemistry, in spite 
of their meeting it as an abundant element in 
animal substances, as an essential accessory to | 
vegetation, as an important element in some of | 
the most valuable seeds, as in fact a perfectly 
characteristic principle of both animal and vege- 
table nutrition, have been baffled in every attempt 
to ascertain its mode of action, and induced to 
regard it as a chemical enigma. 
The specific gravity of | 
M. Le Comte | 
Chaptal, for example, says, “ This principle ap- 
pears to exercise the least influence of all upon | 
substances belonging to either of the three king- 
doms of nature. The action of nitrogen is, in 
fact, so unimportant as far as it is known, that 
we are at fault to assign any reason why nature 
should have been so lavish in its diffusion 
throughout the atmosphere. It has, indeed, been 
considered by some in the light of a vast aerial 
magazine, intended to receive all the gases, ex- 
halations, and vapours, which ascend from the 
earth’s surface, and out of which these are again 
withdrawn, as they may be needed either for the |. 
support of animal life, or to quicken vegetation, 
or for the production of those numerous pheno- 
mena of composition and decomposition which are 
incessantly renovating the surface of the globe.” 
Yet azote is now distinctly known to play a most 
conspicuous part upon both animal and vege- 
table organisms, to supply from the atmosphere 
part of the nourishment of some plants, to sup- 
ply from plants a main part of the nourishment 
of all granivorous animals, to evolve from | 
