NITRIC OXIDE. 



NITROGEN. 



960 



by Henry Lee, London, 1848) ; or causing vesication over the stomach 

 in Asiatic cholera, or for dropping into a carious tooth to relieve tooth- 

 ache. For all other purposes it is very largely diluted. 



In its action on the system it differs from other acids, inasmuch as 

 it does not produce the cooling and thirst-allaying effect which they 

 do, but on the contrary causes a feeling of warmth in the stomach, 

 with thirst and increase of appetite. The use of it continued for some 

 time gives rise to general effects ; an excitement is felt through the 

 whole system ; the pulse becomes quick, the exhalation great ; and an 

 increased secretion from the salivary glands, mucous membranes, the 

 liver, and kidneys is manifest. Perseverance in the use of this agent 

 however at last produces many bad consequences ; and iu persons 

 much disposed to bleeding from the lungs, it almost invariably causes 

 such bleeding to occur, as well as heat in the chest and obstinate cough. 

 Very largely diluted, it furnishes one of the best drinks in fevers 

 accompanied with great prostration of strength. 



It is also a very excellent tonic in many cases, and seems to form 

 the best substitute for the bile where that secretion is scanty. That 

 it greatly augments the secretion of bile, the nature of the evacuations 

 abundantly proves. Hence it differs from almost all other tonics in not 

 causing constipation, but rather the contrary. In calculous diseases 

 of the phosphatic diathesis it has been used with great benefit ; and 

 also, very largely diluted, it has been injected into the bladder as a 

 direct solvent. [LrrnoNTBRirrics.] In the treatment of scrofula it 

 is a most valuable remedy, but its use must be every now and then 

 suspended, owing to the effects which it produces on the stomach. 

 During its use, care must be taken to protect the teeth, by instantly 

 rinsing the mouth. 



It has been regarded as a substitute for mercury in some cases, 

 especially as it projnotes the secretion of saliva. It ought never to 

 be given at the same time as mercury, nor even soon after a dose of 

 any mercurial preparation, since a poisonous nitrate of mercury may 

 be formed in the stomach. Lastly, nitric acid increases the efficacy 

 of many other medicines, such as ammoniacum, cusparia, and opium. 



Nitric acid in the form of vapour was formerly employed as a dis- 

 infecting agent, but it is now almost disused. The vapour must be 

 carefully avoided, as the inhalation is very deleterious. 



Nitric acid in combination with hydrochloric acid, added to a large 

 quantity of water, has been used as a bath in chronic diseases of the 

 liver, particularly in India, but it does not seem entitled to much 

 credit. 



Nitre-hydrochloric acid is a most valuable tonic in some forms of 

 indigestion and debility, in combination with bitters. 



NITRIC OXIDE. [NITROGEN.] 



NITKIDES. [NITROGEN.] 



NITRIFACTION. When organic matters containing nitrogen 

 undergo decay in the presence of alkaline substances, such as lime or 

 potash or their carbonates, a considerable quantity of the nitrogen 

 becomes converted into a nitrate of the base at the expense of atmos- 

 pheric oxygen. When potash is the base present, the matters gene- 

 rally become coated with an encrustation of crystalline nitrate of 

 potash, commonly called nitre : hence the name of the process. Much 

 of the nitre of commerce is thus made. 



NITRILES, a generic name applied in chemistry to compounds 

 which are obtained by removing four equivalents of water from the 

 ammonia salts of certain acids ; thus acetonitrile, or the nitrile of 

 acetic acid, is produced as follows : 



~ 4HO = 



Acetonitrj-1. 



The nitriles are now known to be identical with the cyanides of the 

 positive radicals ; thus acetonitrile is cyanide of methyl : 



C t H 3 N = C 2 N 3 j 



NITRITES. [NITROGEN.] 



NITRO. NITR. Prefixes used in chemistry to denote the presence 

 of nitrous acid (NO,) as a substitute for hydrogen, in the body to 

 which they are attached. Thus nitre-benzole (C^H^NO,) ), nitrani- 

 linr (XCuHjINO,) ). Such compounds when not mentioned under 

 thetr respective names, will generally be found described under the 

 name of the body to which the prefix is added. 



NITROBENZIDE. A nearly obsolete name synonymous with 

 nilnJintzole. [15i ,-vbenzole.] 



NITRO-BENZOIC ACID. [BENZOIC ACID.] 



NITKO-CHLOROBENZOIC ACID. [BENZOIC ACID.] 



NITROCOCCUSIC ACID. (C 16 H ; (NOJ 3 O (I + 2 Aq.) Derived from 

 canninic acid [CARMIXE], by the action of strong nitric acid at a boil- 

 ing temperature. Oxalic acid is formed at the same time, but may be 

 separated by precipitation with nitrate of lead, nitrococcusic acid not 

 being thrown down by that reagent. On evaporating the nitrate from 

 the oxalate of lead precipitate, nitrococcusic acid crystallises out, and 

 may be obtained perfectly pure by two or three recrystallisations. 



Nitrococcusic acid occurs in yellow rhombic plates. It is soluble in 

 water, alcohol, ? rtli'T, and deflagrates violently on being heated. Its 

 solution stains the skin of a yellow colour ; dissolves iron and zinc, 



becoming dark-coloured ; and is decomposed by sulphide of ammonium 

 with separation of sulphur and formation of a new acid not yet 

 examined. The nilrococcuaates have the general formula (C 10 H.,M., 

 ^ ' ' -M a O + #Aq.) ; those of ammonia, potash, baryta, copper, and silver 

 are crystalline and soluble in water. 



NITRO-KRYTHROMANNITE. [EBTTURIC ACID.] 



NITROGEN. This gas constitutes seveuty-nine hundredths, or 



about four-fifths, of the atmosphere. Its name is derived from the 



Greek words vnpov, nitre, and yevi/du, I produce. It was formerly 



called azote, or azotic gas, from a privative, and (art], life, indicating 



Priestley procured it about the same period, and described several of 

 its qualities iu the 'Philosophical Transactions' for 1772; he after- 

 wards called it pJdogisticated air. 



This gas may be obtained by several processes. Dr. Rutherford 

 separated it from the oxygen gas, with which it forms atmospheric air, 

 by repeatedly breathing the same portion of atmospheric air, and 

 agitating it afterwards with a solution of caustic alkali ; this absorbed 

 the carbonic acid formed during respiration, and left the nitrogen gas 

 unacted upon. 



Dr. Priestley procured nitrogen gas by exposing a given volume of 

 atmospheric air to a mixture of sulphur and iron filings ; by this the 

 oxygen was absorbed, and the nitrogen gas left. He also prepared it 

 by some other means. 



The readiest method of obtaining this gas is by the following process : 

 Put a small piece of phosphorus in a little cup fixed to a cork floating 

 on water, and set fire to it ; while burning, hold inverted over it and 

 dipping a little into the water, a glass jar or wide-mouthed bottle 

 containing atmospheric air. During combustion the phosphorus unites 

 with the oxygen of the air to form phosphoric acid, but having no 

 affinity for the nitrogen gas, that remains nearly in a pure state, when 

 it has either stood over the water or been agitated with that liquid, 

 until all the white vapour of phosphoric acid has disappeared. 



Nitrogen may also be separated from atmospheric air by the slow 

 combustion, as it is termed, of phosphorus; that is, by merely exposing 

 a stick of phosphorus, supported by a wire, in a bottle of air inverted 

 over water. 



By the exposure of moistened iron filings or iron borings to air in a 

 bottle inverted over water ; the metal oxidises, and the nitrogen gas is 

 left : this acts even more slowly than the phosphorus in the above 

 experiment. 



By the agitation of mercury and lead in a corked bottle for a few 

 minutes a black powder is formed, which is probably a mixture of an 

 oxide of lead with finely-divided mercury ; nitrogen gas is left. 



The passing of atmospheric air over iron or, better, copper borings, 

 heated to redness in a tube, is a useful method of preparing nitrogen 

 when required on the large scale, but the process does not yield it in a 

 perfectly pure state. 



By exploding a mixture of 100 volumes of air and 42 of hydrogen, 

 water is formed, and about 80 volumes of nearly pure nitrogen gas 

 left. 



Finally, nitrogen, when required absolutely pure, is best prepared by 

 heating a mixture of chloride of ammonium and slightly alkaline 

 nitrite of potash [NITROUS ACID], the nitrite of ammonia thus formed 

 being split up according to the following equation : 



NH 4 O,N0 3 = 4HO 

 Nitrite of ammonia. Water. 



Nitrogen. 



To free the gas from all traces of ammonia, it should be passed through 

 a bottle containing dilute sulphuric acid. 



Nitrogen is transparent, colourless, inodorous, and insipid. Its 

 specific gravity is 0-9713 ; 100 cubic inches of it weighing 30119 grains 

 at 60 Fahr., the barometer marking 30 inches. Its refractive power, 

 compared with air as unity, is 1'020 ; its specific heat, according to 

 Berzelius, being 1'0247. 



Nitrogen is generally considered as an electro-positive element, and 

 in voltaic combinations is attracted to or elicited from the negative 

 surface. Mr. Faraday has, however, found that, according to the nature 

 of the substance decomposed, nitrogen may appear at either pole ; but 

 he concludes, that when it is evolved at the negative one it is a 

 primary result, and when at the positive a secondary one. 



Water dissolves but a very small quantity of this gas : according to 

 Dr. Henry, 100 cubic inches take up only 1'47 cubic inches of the gas; 

 Dr. Dalton states it to be 2'5, and Saussure 4'1 cubic inches. It is 

 fatal to animals when respired by itself, as implied by the term azote ; 

 it extinguishes flame immediately ; no degree of cold and pressure to 

 which this gas has been subjected has condensed it to a fluid form. 



Nitrogen resembles all other elementary bodies in being destitute 

 of acid or alkaline powers ; its affinity for substances, both elementary 

 and compound, appears to be extremely weak, there being very few 

 with which it combines by mere mixture, or by the action of heat 

 under common circumstances. By electricity, however, or by the 

 intense heat which the electric discharge excites, it may be made to 

 combine with oxygen, and the result is nitric acid. The experiment 

 was first made by Dr. Priestley ; but the true nature of the action, 



