NITROGEN. 



239 



being immediately extinguished. It is equally in- 

 capable of supporting animal life by respiration ; 

 not, however, through any operation as a poison, bul 

 simply from the exclusion of oxygen. It is not per- 

 ceptibly absorbed by water. Its peculiar characters, 

 as a distinct substance, are better shown in its chemi- 

 cal combinations. It unites with oxygen in different 

 proportions, and forms compounds possessed of very 

 peculiar chemical properties. Compounds of it with 

 chlorine and iodine may be obtained ; and it is a chief 

 ingredient in the products of the animal kingdom. It 

 unites, too, with hydrogen, forming one of the alka- 

 liesammonia. What purposes are served by the 

 nitrogen in the atmosphere, is not clearly understood. 

 Its most obvious use is as a diluent to moderate the 

 action of oxygen ; but, as it is found to exist in large 

 quantities in all animal substances, it is probably of 

 more direct utility to some part of the animal system. 

 Nitrogen unites with oxygen in four proportions, 

 forming as many direct compounds. These are, I . 

 protoxide of azote, or nitrous oxide; 2. deutoxide of 

 azote, nitrous gas, or nitric oxide; 3. nitrous acid; 

 4. nitric acid. 



Nitrons oxide, or protoxide of azote, was discovered 

 by doctor Priestley, in 1772, but was first accurately 

 investigated by Sir H. Davy, in 1799. The best 

 mode of procuring it is to expose the salt called 

 nitrate of ammonia to the flame of an Argand lamp 

 in a glass retort. When the temperature reaches 

 400 Fahr.,a whitish cloud will rise into the neck of 

 the retort, accompanied by the copious evolution of 

 gas, which must be collected over mercury for accu- 

 rate researches, but, for common experiments, may 

 be received over water. It has all the physical pro- 

 perties of common air. It has a sweet taste, a faint, 

 agreeable odour, and is condensable by about its own 

 volume of water. A taper plunged into it burns 

 with great brilliancy, the flame being surrounded 

 with a bluish halo. Sulphur and most other com- 

 bustibles require a higher degree of heat for their 

 combustion in it than in either oxygen or common 

 air. Specific gravity, I -5277. It is respirable, but 

 not fitted to support life. Sir H. Davy first showed 

 that, by breathing a few quarts of it, effects analogous 

 to those occasioned by drinking fermented liquors 

 were produced. Individuals who differ in tempera- 

 ment are, however, differently affected. Sir H. 

 Davy describes the effect it had upon the following per- 

 sons thus": " Mr James Thomson involuntary laugh- 

 ter; thrilling in his toes and fingers ; exquisite sen- 

 sations of pleasure. A pain in the back and knees, 

 occasioned by fatigue. the day before, recurred a few 

 minutes afterwards. A similar observation, we 

 think, we have made on others ; and we impute it to 

 the undoubted power of the gas to increase the sensi- 

 bility, or nervous power, beyond any other agent, and 

 probably in a peculiar manner. Mr Robert Southey 

 could not distinguish between the first effects and an 

 apprehension of which he was unable to divest him- 

 self. His first definite sensations were a fullness and 

 dizziness in the head, such as to induce the fear of 

 falling. This was succeeded by a laugh which was 

 involuntary, but highly pleasurable, accompanied by 

 a peculiar thrilling in the extremities a sensation 

 perfectly new and delightful. For many hours after 

 this experiment, he imagined that his taste and smell 

 were more acute, and is certain that he felt unusually 

 strong and cheerful. In a second experiment, he felt 

 pleasure still superior, and has since poetically re- 

 marked that he supposes the atmosphere of the high- 

 est of all possible heavens to be composed of this gas. 

 In persons of great susceptibility, the ^inspiration of 

 this gas has been known to produce unpleasant and 

 even alarming symptoms : by such it cannot be in- 

 haled with impunity. . Before concluding our account 



of it, we must explain the theory of its production 

 from the nitrate of ammonia. The sole products of 

 the operation above described are water and the ni- 

 trous oxide gas. Nitrate of ammonia is composed of 



Nitric acid, 54, one proportion ; 



Ammonia J7, one proportion ; 



71 



Nitric acid consists of 



Nitrogen, J 4, one proportion; 



Oxygen, 40, five proportions ; 



51 



and ammonia of 



Nitrogen, 14, one proportion ; 



Hydrogen 3, three proportions. 



17 



By the action of heat, these elements arrange them- 

 selves in a new order. The hydrogen takes so much 

 oxygen as is sufficient for forming water, and the re- 

 sidual oxygen converts the nitrogen both of the nitric 

 acid and of the ammonia into the protoxide of nitro- 

 gen. The decomposition of 71 grains of the salt will 

 therefore yield 



Water, 27, or 3 proportions J 



Nitrous oxide, 44, or 2 proporti 



24, or 3 proportions. 

 >n, 3, or 3 proportions. 

 v/xygeu, 16, or 2 proportions. 

 Nitrogen, 28, or 2 proportions. 



The nitric oxide, nitrous gas, or deutoxide of nitro- 

 gen, was discovered by doctor Hales, but its proper- 

 ties were first investigated by doctor Priestley. It 

 is obtained by the action of diluted nitric acid on 

 metals, the metal abstracting a portion of the oxygen 

 from the acid, and converting it into nitric oxide, 

 which assumes the elastic form. It is not always 

 evolved pure, nitrous acid and nitrogen gas being 

 often formed at the same time. Its purity is en- 

 hanced when the metal copper or quicksilver is used. 

 It is a colourless gas. When mingled with common 

 air, or any gaseous mixture that contains oxygen in 

 an uncombined state, dense, suffocating, acid fumes, 

 of a red or orange colour, are produced, called nitrous 

 acid vapours, which are copiously absorbed by water, 

 and communicate acidity to it. Nitric oxide is thus 

 distinguishable from every other substance, and, for 

 the same reason, affords a convenient test for detect- 

 ing the presence of free oxygen, wherever it exists in 

 aseous mixtures. It does not redden the vegetable 

 lues ; is sparingly soluble in water. Burning sul- 

 phur and a lighted candle are instantly extinguished 

 by it ; but charcoal and phosphorus, if in the state of 

 vivid combustion at the moment of being immersed 

 in it, burn with: increased brilliancy. It is quite irre- 

 spirable, exciting a strong spasm of the glottis, as 

 soon as an attempt is made to inhale it. It is partially 

 decomposed by being passed through red hot tubes. 

 Two volumes of the nitric oxide yielded Sir H. Davy 

 one volume of nitrogen, and about one of carbonic 

 acid, in his decomposition of it by means of burning 

 charcoal, whence it is inferred to consist of equal 

 measures of oxygen and nitrogen gases united, 

 without any condensation. 



Nitrous acid is obtained by exposing nitrate of lead 

 to heat in a glass retort. Pure nitrous acid comes 

 over in the form of an orange-coloured liquid, It is 

 so volatile as to boil at the temperature of 82. Its 

 specific gravity is 1*450. When mixed with water, 

 "t is decomposed, and nitrous gas is disengaged, oc- 

 casioning effervescence. It is composed of one vo- 

 ume of oxygen, united with two of nitrous gas. The 

 various-coloured nitric acids found in commerce are 

 not nitrous acids, but nitric acid, impregnated with 

 nitrous gas. 



Nitric acid was first obtained by distilling a mix- 

 ture of nitre and clay, during the thirteenth century, 

 by Raymond Lully, a chemist of the island of Majorca. 



