MTROQEN. 



NITROGEN. 



and the reault of it, were ascertained by Mr. Cavendish. [NrraiC 

 ACID.] 



Although the projwrtie* of nitrogen are rather of ft negative than a 

 ~ positive description, aod although it* affinities are weak, yet it enter* 

 into the composition of a great number of important compound!. 



With hydrogen it constitute! the alkali AMMONIA, already described ; 

 with chlorine and iodine it give* rice to detonating compound! ; with 

 carbon it form! CYAHOOEX ; and with phosphorus a phosphide : it also 

 combine* with some of the metal* forming nitridet, but they are all very 

 unstable. It enters into the composition of most *j"*i matter* except 

 fat; ii seldom a constituent of the vegetable acids, but invariably 

 forms a part of the vegetable alkalies. 



Although nitrogen itself is fatal to n<t - yet it is a most im- 

 portant constituent of the air, serving to moderate the action of oxygen 

 during combustion, and the too great excitement which that aa 

 respired unmixed would produce on the animal system. It appears 

 also from the experiment* of Majendie that animals cannot live on 

 food that contains no nitrogen. ' 



The equivalent of nitrogen is 14 ; combining volume, 2. 



Oxida of m'fnx/r*. The compounds of nitrogen with oxygen are 

 five ; their names and formula! are : 



1. Protoxide of nitrogen NO 



3. Binoxide of nitrogen . . . . NO. 



3. Xitrou< odd NO, 



4. Peroxide of nitrogen NO, 



i. Nitilc acid NO, 



I. Pntoxidt of nitrogen, Hitroiuofide, or lauyhiagyat. (NO.) This 

 compound was first obtained by Dr. Priestley, who called it dephlogis- 

 ticated nitrous air : he procured it by exposing binoxide of nitrogen 

 to the action of iron, which deprived it of a portion of its oxygen, and 

 reduced it to the state of protoxide of nitrogen. The properties of 

 this gas were minutely examined by Davy. The beet method of 

 procuring it is to subject nitrate of ammonia to moderate heat in a 

 retort ; both the nitric acid and ammonia are decomposed, and their 

 i !< mi ntary oxygen, hydrogen, and nitrogen recombine in such propor- 

 tions as to form water and nitrous oxide gas, thus : 



NII.O.NO, 



4 no 



Wter. 



2SO 



Protoxide of 

 nitrogen. 



One ounce of the nitrate furnishes about one hundred cubic inches 

 of gas. 



Protoxide of nitrogen is colourless and transparent, its smell is 

 peculiar but rather agreeable, and its taste is sweet : 100 cubic inches 

 weigh about 47 grains, and its specific gravity is 1-527. Water absorbs 

 about an equal bulk of this gas, but on being heated, gives it back 

 unchanged. It has no action upon uncombined oxygen, in which it 

 differs remarkably from the binoxide. It is composed of one volume 

 of oxygen and two volume* of nitrogen condensed by combination into 

 two volumes. 



Protoxide of nitrogen supports combustion, and a taper, ignited 

 phosphorus, sulphur, and charcoal burn vividly in it ; at a red hr.it it 

 1* reaolved into it* constituent gases in the proportions stated. \\ li. n 

 a mixture of one volume of this gas and one of hydrogen is fired by 

 the electric ipark, water is produced, and one volume of nitrogen 

 remains : this shows that it must contain half a volume of oxygen, 

 that amount being required to form water with the one volume of 

 1... f I 



Tbu ga* was supposed to be irrespirable, until Davy, in his ' Researches 

 on Nitrous Oxide,' showed that it might be breathed for a short time 

 with impunity. When required for inhalation it should be prepared 

 from pure nitrate of ammonia, should be collected over water, and 

 allowed to stand in contact with that liquid for a few hours. It in 

 most conveniently taken into the lungs from an india-rubber bag, 

 furnished with an ivory mouth piece, the passage into the bag being 

 free and of considerable size. The effects it produces vary considerably 

 with different individuals. After a few inspirations the body of the 

 person usually commence! to describe a kind of rolling movement, 

 similar to that which frequently occurs under tho influence of 

 intoxication, the bag is clutched more earnestly, and inspirations taken 

 more zealously, until in from one to three minutes the subject either 

 suddenly nishes among the bystanders in a state of enthusiastic 

 pugilsim, or shrieks and is convulsed with laughter, or, in a condition 

 of unstable equilibrium, standi blinking at nothing, with a grinning, 

 semi-idiotic gaze. Protoxide of nitrogen has well earned for itself the 

 name of la*yhiny gat, not so much perhaps from the effects it produces 

 on the patient, as from the roars of laughter elicited from those who 

 witness iU inhalation. 



Protoxide of nitrogen may be obtained in the liquid state by subject- 

 ing it to a pressure of about forty atmospheres. Once compressed it 

 may be preserved in a reservoir for two or three days, but soon begins 

 to attack the brass or copper fitting!. On opening the stopcock the 

 fint portions of the liquid freeze into a solid mass, resembling snow ; 

 but it afterward! flows freely, and being received into an open glass 

 remain* fluid for nearly an hour. During the whole time, however, it 

 is slowly evolving gaa. 



Liquid 'protoxide of nitrogen is a colourless, mobile, and \- 

 transparent fluid. A drop let fall upon the akin rapidly evaporate*, 

 producing a jninful burn. Mixed with bisulphide of carbon and 

 exposed to evaporation in vacuo, a reduction of temperature ensues to 

 probably 252 below the freezing ]K>int of water, at all went* to a 

 much lower point than has hitherto been obtained by any other mean*. 

 Metals dropped into liquid protoxide of nitrogen produce a noise as 

 though red-hot iron were immersed in water. Mercury causes the 

 same noise, imtaiitly freezes and affords a bard brittle mass, of the 

 appearance of silver. Potassium floats upon the liquid, but ex|>erience* 

 no change, and the same is the case with charcoal, sulphur, phospho- 

 rus, and iodine : strong sulphuric and nitric acids freeze immediately ; 

 ether and alcohol merely mix with the liquid ; but water is instantly 

 frozen with an almost explosively sudden elimination of gas. 



2. Sinoxide of nitrogen, dfuluxide of anile, or nitric . 

 Although this gaseous body had been obtained by Hales, yet . 



Dr. Priestley that we owe the first distinct account of the method 

 of procuring it and a description of its properties. \Yh< n mi-tain 

 metals such as mercury, or better copper in the state of borings, 

 are put into dilute nitric acid, they are dissolved. 1 

 their solution, owing to the partial decomposition of a pr..]r 

 the nitric acid and the absorption of its oxygen by the metal, giseous 

 biuoxide of nitrogen is plentifully formed and evolved. It lias the 

 following properties : it is gaseous, or permanently clastic, not having 

 been hitherto condensed into a liquid by any degree of cold or pressure 

 to which it has been subjected. It is colourless, and probably tasteless 

 and inodorous; but when an attempt is made to inhale it, it < 

 violent spasm of the glottis by meeting and combining with the oxygen 

 of the air, which converts it into nitrous acid gas, a very dill, nui 

 compound. Its specific gravity is 1 '039 ; 100 cubic inches weighing 

 rather more than 32 grains. Water at 60" dissolves about 11 p. 

 It has no action on litmus paper, nor does it in any way exhibit the 

 properties of on acid ; but as already noticed, nitrous acid is formed as 

 soon as it conies into contact with oxygen, and then it reddens litmus 

 paper; this property distinguishes it from all other gases wli 

 and renders it a test of the presence of uncombined oxygen : tliis w 'a.i 

 the gas first employed by Dr. Priestley in his eudiometrieal rese 

 It supports combustion, if the temperature of the cotul'ii-tii'lr ! 

 sufficient to decompose it into oxygen and protoxide of nitrogen, thus, 

 charcoal and phosphorus immersed in it when they are in vivid c mi 

 bustion, bum splendidly, but a burning candle is extinguished : 

 sulphur also, if only sluggishly burning, is extinguished ; but v. i 

 temperature is raised to near the boiling point it burns readily. It 

 is decomposed when passed through red-hot tubes; and the same 

 effect is produced by a succession of electric sparks. It is also decom- 

 posed when exposed to zinc or iron, which take away half the oxygen 

 and convert it into protoxide of nitrogen. It is soluble in a solution 

 of protosulphate of iron ; the solution has a deep green or brow ni-h 

 colour, and has been used in eudiometry to ascertain the pro j 

 of oxygen in gaseous mixtures ; but it cannot be advantageously so 

 employed. 



It is composed by volume, of 



Fifty cubic inches of oxygen gas = 17*20 grain* 

 Kf ty cubic inches of nitrogen gas- IS'05 



82 25 grain*. 



3. A'itroui acid, kypanitroiu acid (NO,), was discovered by Gay- 

 Lussac, who obtained it by adding excess of binoxide of nitrogen to 

 oxygen gas, confined in a glass tube over mercury, containing a con- 

 centrated solution of potash ; under these circumstances 50 volumes of 

 oxygen unite with 200 volumes of binoxide -of nitrogen, forming 

 nitrous acid which unites with the alkali. This acid may also be 

 obtained by long exposure of binoxide of nitrogen gas to solution of 

 potash, or by exposing to intense cold a mixture of 50 volm 

 oxygen gas with 200 volumes of binoxide of nitrogen gas. By tliis 

 operation the acid is obtained in a liquid state and possesses the follow- 

 ing properties : 



At common temperatures it is green or blue, but at it is colour- 

 less; it is very volatile, so that when exposed to the air, it is rapidly 

 converted into an orange vapour, the density of which i* stated to be 

 1-72. When water is added, the acid is decomposed and converted 

 into nitric acid and nitric oxide, the latter escaping with efferve.- 

 This acid does not readily combine with bases to form salt*, being 

 on tli.-ir admixture converted into nitric acid and binoxide of nitrogen. 

 KHrittt may however be formed by moderately heating certain nitrates, 

 the acid of which then lose* two equivalents of oxygen, nitrous acid 

 remaining in combination with the Ijase. Nitrite of jxitash is thus 

 formed, the nitrate being heated until the oxygen evolved contains 

 nitrogen. Solution of nitrite of ammonia, a convenient source of pure 

 nitrogen, is most advantageounly formed in the following way : one 

 part of starch is gently heated with ten parts of nitric acid, and the 

 nitrous acid gai produced passed into solution of potash, of sp. gr. 1.33, 

 until the solution acquires an acid reaction ; a little caustic potash is 

 then added, so as to render it distinctly alkaline, and the n -Kulting 

 liquid when required for the preparation of nitrogen ix mixed with 

 three times its bulk of a saturated solution of chloride of ammonium. 

 and the whole gently heated; the nitrite of ammonia formed in this 



