M'J' 



ISIT 



1 5, and contain one atom of acid (5-t), 

 with two of water ; it is of a yellow- 

 ish tinge, smokes, and is extremely 

 caustic, dissolving most metals. The 

 pure acid consists of one atom of ni- 

 trogen with five of oxygen (formula, 

 N Os). The commercial specimens 

 are adulterated with oil of vitriol and 

 muriatic acid, which are detected by 

 the occurrence of a precipitate when 

 nitrate of silver or limewater is 

 added ; this does not occur in pure 

 acid. Nitric acid is extensively em- 

 ployed in the laboratory as a solvent, 

 ami, from its active action on many 

 compounds, it readily parts with a 

 portion of its oxygen, oxydizing or- 

 ganic and other bodies presented to 

 it. Its salts are soluble in water, 

 and decrepitate on a hot coal. 



NITRIC OXIDE, NITROUS GAS. 

 Binoxide of nitrogen. This gas is 

 given off when dilute nitric acid acts 

 on a metal ; it turns red in the air, 

 being changed into nitrous acid. 



NITRIFICATION, NITRE 

 BEDS. Nitrates of lime or magne- 

 sia are often artificially formed, and 

 the compound subsequently convert- 

 ed into nitre by boiling with wood ash- 

 es, &c. The production of nitrate of 

 lime in agriculture, to be applied to 

 the field and form steeps, is worthy of 

 attention ; this is readily effected by 

 mixing animal and vegetable rubbish 

 with air-slacked lime in loose heaps 

 of any desired length, and six feet 

 wide by three feet high ; these should 

 be arranged under a shed, to protect 

 them from rain and heat, and kept 

 moist with urine, blood, ditch water, 

 and animal or putrescent fluids ; the 

 heaps should be built on tempered, 

 dry ground that will not absorb fluid, 

 and occasionally spaded over. In 

 from four months to one year, ac- 

 cording to the heat and abundance of 

 animal matter, the heaps will be rich 

 enough for use as a top-dressing, or 

 may be washed, to separate the ni- 

 trate : as much of the nitre-bed sub- 

 stance as contains 100 pounds of ni- 

 trate may be used as a top-dressing 

 to the crop, or put into compost with 

 other fertilizers. As soon as one bed 

 is removed another should be erect- 

 520 



ed, and thus a succession formed, in 

 which every kind of offensive garbage, 

 night soil, and every kind of animal 

 texture will be consumed with profit to 

 the farmer, and one of the most active 

 manures for poor soils created. Peat, 

 fine mould, river mud, and such sub- 

 stances may be used to mix with the 

 nitre bed when a basis is wanted. 



The rich mould of the forest, old 

 manure heaps, damp calcareous tracts 

 of land are all natural nitre beds, 

 which may be put up without any or- 

 ganic matter, but in which, the more 

 we add, the more rapidly nitrates are 

 formed. 



NITRITES. Salts of nitrous acid. 

 They are not of agricultural impor- 

 tance. 



NITROGEN. Azote. An ele- 

 mentary gas, colourless, inodorous, 

 inactive, of nearly the same weight 

 as air, incapable of sustaining life or 

 flame, forming 8-lOths of the atmo- 

 sphere, and existing in nitric acid, 

 ammonia, cyanogen, and numerous 

 compounds. It is abundantly present 

 in animal textures, and forms a mi- 

 nute part of all plants, rarely attain- 

 ing 5 per cent. Its equivalent is 142, 

 symbol N. Its compounds with oxy- 

 gen are numerous ; of these, nitric 

 acid is the most important ; nitric 

 oxide, or the binoxide, seems to be a 

 compound radical. With hydrogen 

 it forms ammonia, a substance of 

 great importance, of which we shall 

 treat here. 



Ammonia {volatile alkali), in the 

 pure state, is a very pungent, inflam- 

 mable gas, consisting of one equiva- 

 lent of nitrogen (14 2) and three of 

 hydrogen (3), and having a combi- 

 ning number of 17-3 : symbol N H3. 

 "Water dissolves 700 to 800 times its 

 volume of the gas ; the solution, or 

 liq. ammonia, of sp. gr. 87, contains 

 32 per cent, ammonia : it becomes 

 caustic, pungent, and alkaline. It is 

 the usual form in which this body is 

 known. It readily unites with acids, 

 forming salts of ammonia, of which 

 the sesquicarbonate, or sal volatile, 

 preserves the odour. 



Ammonia is one of the products of 

 fermenting animal matter, and its 



