NITER 



4241 



NITROGLYCERINE 



NITER, ni't'r. See SALTPETER. 



NITRATES, ni' trayts, are salts of nitric acid. 

 Some of them, such as lead, iron and silver, are 

 useful in medicine; others are utilized in the 

 manufacture of fireworks, as barium nitrate, 

 which gives a green light, and strontium nitrate, 

 which gives a beautiful red light. It is as 

 fertilizers, however, that they are chiefly im- 

 portant. Worn-out soil needs new supplies of 

 nitrogen in order to produce good crops. Great 

 fields of Chile saltpeter (sodium nitrate) in 

 South America supply quantities of natural 

 fertilizers (see pages 1332 and 1334 of the arti- 

 cle CHILE) ; and ordinary manure contains a 

 large per cent of nitrogen compounds. Decay- 

 ing vegetable matter is converted into nitrogen 

 compounds by the action of microscopic organ- 

 isms in the air and soil. See FERTILIZER. 



NITRIC, ni'trik, .ACID, an important min- 

 eral acid (aqua jortis in the arts), largely used 

 in the manufacture of coal-tar dyes, high-power 

 explosives (see NITROGLYCERINE; GUNCOTTON), 

 as an etching fluid in the arts and as a medi- 

 cine. It was first prepared about the ninth 

 century by an Arabian chemist, Geber, who 

 distilled a mixture of saltpeter, cyprian vitriol 

 (copper sulphate) and alum. It is now pre- 

 pared commercially by distilling Chile saltpeter 

 (sodium nitrate) and concentrated sulphuric 



In a pure state it is an unstable, fuming, col- 

 orless fluid, capable of burning organic tissues 

 by chemical action. On exposure to air it de- 

 composes into lower oxides, and brown fumes 

 of nitrogen peroxide appear. Seventy-six per 

 cent of the acid is oxyuen, which is readily 

 n up, making the acid a powerful oxidizing, 

 or reducing, agent. Animal and vegetable mat- 

 ter are quickly corroded by it, giving charac- 

 teristic yellow stain. It never occurs in a free 

 state, but is found abundantly in combination 

 with potash, soda, lime and magnesia. Traces 

 of it arc also di.-n-rnibl- in rain water after a 

 thunderstorm. With sodium, potassium and 

 ments, it forms soluble salts called 



NITROGEN, ni'trojin, a gaseous, nonme- 

 tallic element comprising about seventy-nine 

 per " 1'irless, tasteless and 



odorless, and ia f. Oi.m 



hydrogen but lighti r than air, of whieli 

 seventy-right JT o-nt (l>y \olumr). Without 

 mtnm. n in eOIN ;<l:mts and an:: 



(nuM not h\<\ It does not easily combine with 



<-os as does oxygen, and tin ; 

 to dilute the oxygen in the air. 



Plants as a rule cannot absorb the nitrogen 

 from the air and must therefore draw their 

 supply from the nitrogen compounds in the soil. 

 Enriching soil with manure, or with some nat- 

 ural fertilizer, such as guano or Chile saltpeter, 

 means, chiefly, putting a much greater quantity 

 of nitrogen compounds into it to be taken up 

 by plant roots. Because it is feared that the 

 supply of nitrogen fertilizers, such as guano, 

 will soon be exhausted, scientists are constantly 

 trying to find a way to make nitrogen com- 

 pounds artificially from the free nitrogen of the 

 air, but these attempts have not been very 

 successful (see FERTILIZER). 



Nitrogen was discovered to be a constituent 

 of air in 1772 by Professor Rutherford of Edin- 

 burgh University, who found that there was a 

 new gas left when all the oxygen had been 

 taken out. It was named nitrogen because it 

 was known to be a constituent of niter (potas- 

 sium nitrate). With oxygen (which see) it 

 forms five oxides, three of which are important. 

 Nitrous oxide is the anesthetic laughing gas, 

 used importantly in dental work; nitric oxide 

 is a colorless gas containing equal volumes of 

 nitrogen and oxygen; nitrogen peroxide is a 

 reddish-brown gas formed by uniting nitric 

 oxide and oxygen. 



In 1911-1912 a new form of nitrogen was an- 

 nounced by Strutt. He observed that after an 

 electric discharge in an atmosphere of nitrogen, 

 the nitrogen continued to glow and give off 

 light, and that under these conditions it com- 

 bined easily with the metals sodium and mer- 

 cury when heated, and changed ordinary yel- 

 low phosphorus to red phosphorus. The latter 

 is now used to some extent in the manufacture 

 of matches, as a substitute for yellow phos- 

 phorus, which is highly poisonous and danger- 

 ous to handle (sec MATCHES). 



NITROGLYCERINE, ni tro gits' er in, a highly 

 explosive compound made by pouring one part 

 of glyernne into a cooled mixture of four \ 

 concentrated sulphuric acid and one part con- 

 centrated nitric acid. The nit roglyri -rine crys- 

 tallizes out win ii the acids arc pound into 

 wat a light yellow or colorless, oily 



liquid, almost insoluble in water, sweet to tin- 

 taste and very poisonous. It is not easily set 

 . but 1 Minis with a greenish fl.une. and 

 itod to 180 degrees decomposes with 

 Aplosivr violence. It may be exploded by a 

 severe jar, but is easiest set off with a detona- 

 tor containing fulminate of mercury. 

 volume of gas liberated is about. 10,000 tim< 

 the volume of the nitroglycerine. Compared 



