KIT 



[315 J 



NIT 



regular crystals ; it is white, semi- 

 transparent, and brittle ; salt and 

 cold in taste. When thrown on 

 hot coals, it burns with a sparkling 

 bright light, and with a crackling 

 noise. It crystallizes in six-sided 

 prisms, terminated by a dihedral 

 summit, and retains no water of 

 crystallization. The crystals are 

 permanent, and soluble in seven 

 parts of water at 60, and in less 

 than their own weight at 212. 

 The principal supply of nitre is 

 from India. One of the most re- 

 markable localities of nitre in 

 Europe, is in the Pula, or cavity of 

 Molfetta, in the kingdom of Naples. 

 This cavity, which is about one 

 hundred feet deep, contains several 

 grottoes or caverns, in the interior 

 of which is found nitre in crusts, 

 attached to compact limestone. 

 "When these crusts are removed, 

 others appear in about a month. 

 The various sources of native nitre 

 not being sufficient to supply the 

 great demand there exists for it, it 

 is manufactured wholesale, in the 

 following manner. Rubbish, con- 

 sisting of lime, mortar, plaster, and 

 earth, is mixed up in heaps, under 

 sheds, with decaying vegetables 

 and refuse matter, and left to rot; 

 the masses being occasionally 

 moistened with animal fluids, as 

 urine, blood, &c. The nitrogen, 

 disengaged from the corrupting 

 mass, unites with the oxygen of 

 the atmosphere, 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 vhpov, nitre, and 

 yewdu), to produce, Gr.) Called 

 also azote. Nitrogen was disco- 

 vered in 1772 by Prof. Rutherford, 

 of Edinburgh : it may be obtained 

 by several processes, the object of 

 most of which is to take away 

 the oxygen gas from atmospheric 



air, of which nitrogen constitutes 

 above four-fifths, or eighty per cent., 

 the rest being principally oxygen. 

 In its pure state, nitrogen is re- 

 markable 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 alkaline; pos- 

 sesses neither taste, colour, nor 

 smell ; nor does it directly combine 

 with any known substance. Yet 

 when made by peculiar manage- 

 ment to unite with oxygen, hy- 

 drogen, or carbon, nitrogen forms 

 some of the most energetic com- 

 pounds we possess; 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 am- 

 monia, likewise an energetic com- 

 pound, but of an opposite nature ; 

 while united with carbon and 

 hydrogen, it forms prussic acid, the 

 most virulent poison in existence. 



The absorption of nitrogen during 

 respiration, was one of the results 

 Dr. Priestley deduced from his 

 experiments ; and this fact, though 

 often doubted, appears, on the 

 whole, to be tolerably well as- 

 certained by the inquiries of 

 Davy, Pfaff, and Henderson. 

 With regard to the respiration 

 of cold blooded animals, it 

 has been satifactorily established 

 by the researches of Spallanzani, 

 and more especially by those of 

 Humboldt and Proven9al, on fishes, 

 that nitrogen is actually absorbed. 

 A confirmation of this result has 

 been obtained by Macaire and 

 Marcet, who have found that the 

 blood contains a larger proportion 

 of nitrogen than the chyle, from 

 which it is formed. 



Nitrogen has been recently found, 

 by Dr. Daubeny, to be contained 



