Nitrogen dioxide

“ The nitrogen permeates the blood while the oxygen is consumed and exhaled in the form of carbon dioxide. The longer a man is exposed to the pressure the more nitrogen does he absorb. When the pressure is released suddenly the nitrogen begins to froth, just as a bottle of soda water does when the stopper is removed. ”

“ Of the air's various gaseous constituents, nitrogen, argon and helium and its companions are what the chemists call inert substances, i. e., they are slow and backward about entering into chemical alliances. However important nitrogen is in the life of living things, neither is it, nor are these other inert gases, known to exert as atmospheric components specific actions on living human beings. They may, therefore, be eliminated from consideration, as may also the minute traces of hydrogen and ammonia, and our attention may be focused at once upon oxygen and carbon dioxide. ”

“ Traces of nitrous and nitric acid are also present in the air, produced by the direct combination of nitrogen and oxygen occurring as the result of the electric spark during lightning.
Carbonic Acid or carbon dioxide is always present in air, in the proportion of 3·36 to 4 parts in 10,000; but in impure air may be present in much larger amount. It is a heavy gas, incapable of supporting combustion, and therefore of supporting animal life. Being a heavy gas, it tends to accumulate where it is produced, as about lime-kilns by the heating of chalk. ”

“ The hydrogen, on coming in contact with the atmosphere, ignites and adds itself to the hydrosphere. The carbon dioxide is in part decomposed by plants, and adds to the supply of atmospheric oxygen. The nitrogen, being comparatively inert, doubtless gradually accumulates in the air and has thus come to be its preponderant constituent. ”

“ In other words these bacteria can build up organic matter from purely mineral sources by assimilating carbon from carbon dioxide in the dark and by obtaining their nitrogen from ammonia. The energy liberated during the oxidation of the nitrogen is regarded as splitting the carbon dioxide molecule,—in green plants it is the energy of the solar rays which does this. ”

“ The method of manufacture exclusively employed until recent years, and still in very extensive use, is much more complicated. The reactions are quite involved, but the conversion of water, sulphur dioxide, and oxygen into sulphuric acid is accomplished by the catalytic action of oxides of nitrogen. The reactions are brought about in large lead-lined chambers, into which oxides of nitrogen, sulphur dioxide, steam, and air are introduced in suitable proportions. ”

“ Oxygen and carbon have also a very strong affinity, and readily form the stable product carbonic dioxide gas. Nitrogen, on the other hand, is a very inert substance; its molecule consists of two atoms of itself which are bound together by a strong affinity, and can only be coaxed with difficulty into combinations with other elements, forming compounds which are, as it were, artificial structures, and very unstable. ”

“ The choice of absorbents and the order in which the gases are to be estimated is strictly limited. Confining ourselves to cases where titration methods are not employed, the general order is as follows: carbon dioxide, olefines, oxygen, carbon monoxide, hydrogen, methane and nitrogen (by difference) . This scheme is particularly applicable to coal-gas. Carbon dioxide is absorbed by a potash solution containing one part of potash to between two and three of water; the stronger solution absorbs about 40 volumes of the gas. ”

“ That there are a number of intermediate products formed and that nitration also takes place during the formation of these intermediate products is shown by the following. A small quantity of the acids were placed in a test tube and covered with concentrated nitric acid. This was suspended in an H2SO4 bath and a thermometer inserted so as to observe the temperature. On being gently warmed the nitric acid and the resin began to react with a rapid evolution of carbon dioxide and oxides of nitrogen. ”

“ Experiment soon showed that carbon was undoubtedly taken from the air, and that its source was the carbon dioxide poured into the air by fires and by the breathing of animals. It soon became obvious too that plants obtain from the soil water and inorganic salts containing phosphorus, sulphur, potassium, calcium, and so on; but for a long time the source of the plants’ supply of nitrogen was not definitely decided. Four-fifths of the air was known to be nitrogen. The soil was known to contain a small percentage of that element, which however amounts to four or five tons per acre. ”

“ For after the mephitic portion is absorbed by a caustic alkaline lixivium, the remaining portion is not rendered salubrious; and although it occasions no precipitate in lime-water, it nevertheless extinguishes flame and destroys life." Such is the doctor's account of the discovery of nitrogen, which may be separated from the oxygen in the air in a very simple manner. The atmosphere is the great storehouse of nitrogen, and four-fifths of its prodigious volume consist of this element. ”

“ At the high temperature of the electric arc in air, the molecules of nitrogen and oxygen dissociate into their atoms. The air comes out of the arc, charged with about one per cent. of nitric oxide, and after that—"
"Jump the details, idiot! Can't you move faster than a paralytic snail? What's the final result?"
"The result is, sir," answered Herzog, meek and cowed under this harrying, "that calcium nitrate is produced, a very excellent fertilizer. It's a form of nitrogen, you see, directly obtained from air." ”

“ In short, under all circumstances, and in all places, the relation subsisting between the oxygen and nitrogen is constant; and though, no doubt, many local circumstances exist which may tend to modify their proportions, these are so slow and partial in their operations, and so counterbalanced by others acting in an opposite direction, as to retain a uniform proportion between the main constituents of the atmosphere, and to prevent the undue accumulation of one or other of them at any one point. ”

“ But these investigations have also shown that while most compounds decompose with rise of temperature, this one, nitric oxide, becomes more stable, the higher the temperature. Thus at 3000° five per cent, of the mixture of nitrogen and oxygen will unite to form nitric oxide. To get a fair yield of our product we must therefore expose air to an enormously high temperature. ”

“ Nitrogen alone is a sufficient diluent of the necessary oxygen. Are these rare gases purposeless? I am intensely curious about them. Are there outcasts also among the elements? Are these gases dead elements? One of them, helium, is a transmuted emanation of radium. Is it the ghost of radium? Nitrogen, with which they are found mechanically mingled, is the element of fermentation and decay. One feels upon the brink of a notable discovery. These dead gases, these ghosts of elements herding with the vapour of dissolution, nitrogen, cannot be entirely ineffective. ”

“ Mix nitrous gas and air together in a jar over water, and the nitrous gas takes away the oxygen, and then the water sucks up the mixed oxygen and nitrous gas, and that part of the air which weakens the oxygen is left behind. Burning phosphorus in confined air will also take all the oxygen from it, and there are other ways of doing the same thing. The portion of the air left behind is called nitrogen. ”

“ I should be a good deal puzzled to say what nitrogen does in the air: he is there as an inert body, and leaves all the business to the oxygen. When we breathe, for instance, the nitrogen enters our lungs together with its inseparable companion, but it goes out as it went in, without leaving a trace of its passage. Nevertheless, as sometimes happens among men, the one who does nothing takes up the most room. Nitrogen alone occupies four-fifths of the atmosphere, where it is of no other use than to moderate the ardent activity of king oxygen, who would consume everything were he alone. ”

“ The same odor is perceptible around stables and other places where animal matter is decomposing. All animal muscle, certain parts of plants, and other organized substances, consist of compounds containing nitrogen. When these compounds undergo combustion, or are in any manner decomposed, the nitrogen which they contain usually unites with hydrogen, and forms ammonia. In consequence of this the atmosphere always contains more or less of this gas, arising from the decay, etc., which is continually going on all over the world. ”

“ If only consisting of nitrogen, the human race would also die, because this element is incapable of supporting life; people would be suffocated, in fact.
Therefore, a judicious mixture of the two is essential to the life of animals. Generally, in a hundred parts of air by weight there are seventy-six parts of nitrogen to twenty-three of oxygen.
Besides these two gases, there is also a quantity of carbonic acid gas in the air, given off by all the fires and animals in the world. Of course, its amount is much greater in the great towns and manufacturing centers than in country districts. ”

“ In all these processes the action of the gas is impeded by the bulky presence of its fellow constituent of air, nitrogen. We may say, for instance, in homely phrase, that whenever a fire burns there are four volumes of nitrogen tending to extinguish it for every volume of oxygen supporting its combustion, and to the same degree the nitrogen interferes with all other processes of atmospheric oxidation, of which most metallurgical operations may be given as instances. ”

“ For this reason nitrous oxide formed by the condensation of two permanent gases is a substance which is somewhat easily converted into a liquid; again, nitric acid, which is formed from elements which are permanent gases, is a liquid, whilst, on the contrary, nitric oxide, which is formed without contraction and is decomposed without expansion, remains a gas which is as difficult to liquefy as nitrogen and oxygen. ”

“ Similarly the oxygen in the atmosphere is its most essential constituent, being required in all processes of oxidation (i.e., combustion) , whether in living organisms or in the inanimate world. Nitrogen serves as a diluting agent. It is incapable of101 supporting life alone; and many of the fatal accidents which have occurred through men descending deep wells without first testing, by means of a lit candle held well below them, the quality of the air near the bottom, have been due to an accumulation of nitrogen in the well. ”

“ When it became known (Chapter V., Note 4 bis) that the nitrogen obtained from air (by removing the oxygen, moisture and CO2, by various reagents) has a greater density than that obtained from the various (oxygen, hydrogen and metallic) compounds of nitrogen, it was a plausible explanation that the latter contained an admixture of hydrogen, or of some other light gas lowering the density of the mixture. ”

“ The nitric acid, as it becomes free, gives a part of its oxygen to the phosphorous compound, and the nitrous acid, in a nascent state, is at once reduced by the ammonium chlorid. There are two sources of error which must be guarded against in the work; a portion of the nitrogen may escape reduction to the elementary state, or some of the nitrate may fail to be decomposed. These errors are easily avoided if the reaction be begun slowly, so that the evolution of gas may be gradual. ”

“ When burning coal, however, the percentage of nitrogen is obtained by subtracting the sum of the percentages by volume of the other gases from 100. Thus if an analysis shows 12.5 per cent CO 2 , 6.5 per cent O, and 0.6 per cent CO, the percentage of nitrogen which ordinarily is the only other constituent of the gas which need be considered, is found as follows:
The action of the hydrogen in the volatile constituents of the fuel is to increase the apparent percentage of the nitrogen in the flue gases. ”

“ There is a beautiful adjustment in the constitution of the atmosphere to the nature and necessities of living beings. The energy of the pure oxygen is tempered, yet not too much weakened, by the admixture of nitrogen. The carbonic acid, which alone is noxious to life, is mixed in so minute a proportion as to be harmless to animals, while it is still beneficial to plants; and when the air is overloaded with watery vapour, it is provided that it shall descend in rain. ”

“ This gas is heavier than air, and supports combustion nearly as energetically as oxygen, as may be shown by introducing a piece of ignited phosphorus into a jar of this gas. It will not, however, support the life of small animals, such as mice, which introduced into it die very quickly.
The next compound of nitrogen with oxygen, when one proportion of nitrogen unites with two of oxygen, is termed nitric oxide gas. It may be easily procured by heating in a retort some copper turnings in dilute nitric acid. ”

“ Blow a candle out; and while the wick is still red, hold the candle (by a piece of wire,) in the bottle of oxygen gas; the wick will instantly ignite, and burn brilliantly.
(Burning sulphur emits a blue flame, when immersed in oxygen gas.)
Q. What is nitrogen?
A. Nitrogen is another invisible gas. It will not burn, like hydrogen; and [Pg 36] an animal cannot live in it: it abounds in animal and vegetable substances, and is the chief ingredient of the common air. [9]
[9] Nitrogen gas may easily be obtained thus:—Put a piece of burning phosphorus on a little stand, in a plate of water ”

“ When it arrives there it escapes from the blood, is exhaled, and is at once replaced by the new oxygen and the new nitrogen which arrive from outside. The nitrogen absorbed in aspiration at the same time as the oxygen is found to be of very much the same quantity when it goes out. There has therefore been no appreciable absorption of nitrogen. Now, this slow combustion causes the heat of our body; in fact, what is called the animal-heat is due to the caloric set free at the moment when the oxygen is converted into carbonic acid, in the same way as in all combustion of carbon. ”