N I T 



[ 130] 



NOD 



masses being occasionally moistened wkh 

 animal fluids, as urine, blood, &c. The 

 nitrogen, disengaged from the corrupting 

 mass, unites with the oxygen of the at- 

 mosphere, and forms nitric acid ; this, 

 combining with the potash furnished by 

 the vegetable substances, produces an 

 impure nitre. The salt is collected, and 

 afterwards washed and purified. 

 NI'TROGEN. (from virpov, nitre, and 

 ytvvdb}, to produce, Gr. ) Called also 

 azote. Nitrogen constitutes about four- 

 fifths, or eighty per cent, of common air ; 

 the rest being principally oxygen. In its 

 pure state, nitrogen is remarkable for its 

 negative qualities ; that is to say, for the 

 difficulty with which it enters into combi- 

 nation with other matters. Thus, it is 

 neither combustible, nor a supporter of 

 combustion ; it is neither acid, nor alka- 

 line ; possesses neither taste nor smell ; 

 nor does it directly combine with any 

 known substance. Yet when made by 

 peculiar management to unite with oxygen, 

 hydrogen, or carbon, nitrogen forms some 

 of the most energetic compounds we pos- 

 sess ; thus, mixed with oxygen, it forms 

 atmospheric air ; united with oxygen, it 

 forms aquafortis, the most corrosive of 

 liquids ; united with hydrogen, it forms 

 the volatile alkali, or ammonia, likewise 

 an energetic compound, but of an oppo- 

 site nature ; while united with carbon and 

 hydrogen, it forms prussic acid, the most 

 virulent poison in existence. 



The existence of nitrogen in animal and 

 vegetable life may be considered as se- 

 condary, that is, derived from the atmo- 

 sphere in the first instance. There is 

 also every reason to suppose that it can- 

 not be absent from numerous rocks which 

 contain the organic remains of animals 

 that have been entombed living, or at 

 least with their flesh upon them. We 

 have direct evidence in coal that nitrogen 

 forms a portion of what may be con- 

 sidered solid rock. Dr. Thomson found 

 it to constitute 15-96 per cent, of the 

 Newcastle caking coal, and there is good 

 reason for supposing that this is rather an 

 tinder-estimate of the amount of nitrogen 

 contained in some coal, judging from the 

 abundance of ammoniacal products given 

 out during the distillation of coal in gas- 

 works. 



The absorption of nitrogen during re- 

 spiration, was one of the results Dr. 

 Priestley had deduced from his experi- 

 ments ; and this fact, though often 

 doubted, appears, on the whole, to be 

 tolerably well ascertained by the inquiries 

 of Davy, Pfaff, and Henderson. With 

 regard to the respiration of cold-blooded 

 animals, it has been satisfactorily esta- 

 blished by the researches of Spallanzani, 



and more especially by those of Hum- 

 boldt and Provencal, on fishes, that ni- 

 trogen is actually absorbed. A confirma- 

 tion of this result has been obtained by 

 Macaire and Marcet, who have found 

 that the blood contains a larger propor- 

 tion of nitrogen than the chyle, from 

 which it is formed. 



Nitrogen has been recently found, by 

 Dr. Daubeny, to be contained very gene- 

 rally in the waters of mineral springs. 

 The king's bath, at Bath, evolves 96'5 per 

 cent, of nitrogen, 3'5 oxygen, and some 

 carbonic acid. The hot-well at Bristol 

 evolves 92 per cent, nitrogen, and 8 oxy- 

 gen. The springs at Buxton, Bakewell, 

 and Stony Middleton, Derbyshire, evolve 

 nitrogen only. Those of the Spas, in 

 Germany, yield various proportions, as 

 do the other thermal springs in other 

 parts of the globe. 



The easiest mode of procuring nitrogen 

 is to abstract from atmospheric air, by 

 the combustion of phosphorus or hydro- 

 gen, the oxygen with which it is asso- 

 ciated. Its specific gravity is 0*9722. It 

 forms one of the fifty-five simple, or 

 elementary bodies. Prout. De la Heche. 

 Roget. Phillips. 



NI'VEOTJS. (niveus, Lat.) Snowy ; resem- 

 bling snow ; of a snow-white colour. 



NOA'CHIAN. Pertaining to the great deluge 

 related by Moses, from which Noah and 

 his family were saved, and thus called 

 after Noah. 



NODE, (nodus, a knot, Lat. nodus, Fr. 

 nado, It.) A hard knot or swelling, a 

 bump, or rising. 



In astronomy, the nodes of a satellite's 

 orbit are the points in which it intersects 

 the plane of the orbit of a planet. The 

 ascending node is the point through which 

 the body passes in rising above the plane 

 of the ecliptic, and the descending node 

 is the point through which the body 

 passes in sinking below the plane of the 

 ecliptic. 



NOCTI'VAGANT. } (from nox, the night, and 



NOCTI'VAGOUS. $ vagor, to wander, Lat.) 

 A name given to such animals as wander, 

 in search of prey, during the night. 



NODOSA'RIA. A genus of orthocerata, found 

 only fossil. They are polythalamous 

 univalves. 



NO'DOUS. Knotty ; full of knots. 



NO'DCLAR. In the form of a nodule or 

 small lump. 



NO'DULAR IRON ORE. A variety of argil- 

 laceous oxide of iron ; occurring in masses, 

 varying from the size of a walnut to that 

 of a man's head. Their form is spheri- 

 cal, oval, or nearly reniform, or sometimes 

 like a parallelepiped with rounded edges 

 and angles. They have a rough surface, 

 and are essentially composed of concentric 



