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NITROGEN [symbol N., atomic weight 14...
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See also:NITROGEN [See also:symbol N., atomic See also:weight 14.01, 0=16] . A non-metallic chemical See also:element, first isolated in 1772 by D. See also:Rutherford, who showed that on removing See also:oxygen from See also:air a See also:gas remained, which was incapable of supporting See also:combustion or respiration. Nitrogen forms approximately 79% by See also:volume (or 77% by weight) of the See also:atmosphere; actual values are: % by volume—79.07 (See also:Regnault), 79.20 (See also:Dumas); %by weight—76.87 (Regnault), 77.00 (Dumas), 77.002 (Levey), 76.900 (See also:Stas), 77.010 (See also:Marignac). No absolutely accurate determinations appear to have been made recently. See also:Free nitrogen is also found in some natural See also:waters and has been recognized in certain nebulae. In the combined See also:state nitrogen is fairly widely distributed, being found in See also:nitre, See also:Chile See also:saltpetre, ammonium salts and in various See also:animal and See also:vegetable tissues and liquids. It is invariably See also:present in soils, where compounds are formed by nitrifying bacteria. Nitrogen may be obtained from the atmosphere by the removal of the oxygen with which it is there mixed. This may be effected by burning See also:phosphorus in a confined volume of air, by the See also:action of an alkaline See also:solution of See also:pyrogallol on air, by passing air over heated See also:copper, or by the action of copper on air in the presence of ammoniacal solutions. It is also prepared by See also:heating ammonium nitrite (or a mixture of See also:sodium nitrite and ammonium chloride): NH4NO2=2H20+N2; by heating a mixture of ammonium nitrate and chloride (the See also:chlorine which is simultaneously produced being absorbed by See also:milk of See also:lime orby a solution of sodium hydroxide) : 4NH4NO3+2NH4CI =5N2 +C12+12H20; by heating ammonium dichromate (or a mixture of ammonium chloride and See also:potassium dichromate) : (NH4)5Cr2O7 =Cr203+4H2O+N2; by passing chlorine into a concentrated solution of See also:ammonia (which should be present in considerable excess) : 8NH3+3C12=6NH4Cl+N2; by the action of hypochlorites or hypobromites on ammonia: 3NaOl3r±2NH3=3NaBr+3H20+N2; and by the action of See also:manganese dioxide on ammonium nitrate at 180-200° C. It is also formed by the reduction of nitric and nitrous oxides with See also:hydrogen in the presence of platinized See also:asbestos at a red See also:heat (G. v. Knorre and K. See also:Arndt, Ber., 1899, 32, p. 2136) ; by the oxidation of See also:hydroxylamine (ibid., 1900, 33, p. 30) ; and by the See also:electrolysis of See also:hydrazine and its salts (E. Ch. Szarvasy, Jour. Chem. See also:Soc., 1900, 77, p. 603). The See also:chief importance of nitrogenous compounds depends upon their assimilation by living See also:plants, which, in their development, absorb these compounds from the See also:soil, wherein they are formed mainly by the action of nitrifying bacteria. Since these compounds are essential to plant See also:life, it becomes necessary to replace the amount abstracted from the soil, and hence a demand for nitrogenous See also:manures was created. This was met in a very large measure by deposits of natural nitre and the products of artificial nitrieres, whilst additional supplies are available in the ammoniacal liquors of the gas-manufacturer, &c. The possible failure of the nitre deposits led to attempts to convert atmospheric nitrogen into manures by processes permitting economic success. See also:Combination can be made in five directions, viz. to See also:form (1) oxides and nitric acids, (2) ammonia, (3) readily decomposable nitrides, (4) cyanides, (5) cyanamides. Additional information and CommentsThere are no comments yet for this article.
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