Nitrogen

“ The changes which nitrogen undergoes, from plants to animals, or, by decomposition, to the form of ammonia in the atmosphere, are as varied as those of carbon and the constituents of water. The same little atom of nitrogen may one year form a part of a plant, and the next become a constituent of an animal, or, with the decomposed dead animal, may form a part of the soil. If the animal should fall into the sea he may become food for fishes, and our atom of nitrogen may form a part of a fish. ”

“ Whence do animal substances derive all this nitrogen? Animals live only upon vegetable productions containing little nitrogen; can they then procure all they require from this source alone? Again, does the act of digestion produce any chemical alteration upon the food of animals, that their excretions should be a better manure,—should be richer in nitrogen than the substances on which they feed? Does theory throw any light upon the opinion generally entertained among practical men upon this point? ”

“ The nitrogen in the soil is almost entirely in organic compounds; that is, the nitrogen (which is a gas in the free, or uncombined, state) is united or combined with other elements, notably with carbon, hydrogen, and oxygen, in the form of partially decayed vegetable or organic matter. (By organic matter we mean matter which has been formed by the growth of some organism, either plant or animal, as grass or flesh.) Plants cannot use the free nitrogen of the air as plant food, neither can they use the organic compounds of nitrogen which occur in the soil. ”

“ The compounds of nitrogen, however, cannot readily be obtained from this source, since at any ordinary temperature nitrogen is able to combine directly with very few of the elements.
In certain forms of combination nitrogen occurs in the soil from which it is taken up by plants and built into complex substances composed chiefly of carbon, hydrogen, oxygen, and nitrogen. Animals feeding on these plants assimilate the nitrogenous matter, so that this element is an essential constituent of both plants and animals. ”

“ We have already made some reference to this gas when speaking of the atmosphere and its constituents, of which nitrogen is the principal. From its life-destroying properties it is called “azote” by French chemists, and when we wish to obtain a supply of nitrogen all we have to do is to take away the oxygen from the air by burning phosphorus on water under a glass. Nitrogen is not found frequently in solid portions of the globe. It is abundant in animals. It is without colour or smell, and can be breathed in air without danger. ”

“ Nitrogen is found in plants to the extent of from 1 to 4 per cent.
Nitric Acid.—This, the most important compound of nitrogen and oxygen, can be produced by sending a current of electric sparks through a mixture of its constituents, but in this way it can be obtained only in extremely small quantity. It is much more abundantly produced when organic matters are decomposed with free access of air, in which case the greater proportion of their nitrogen combines with the atmospheric oxygen. ”

“ Nitrogen, the remaining plant-element, is a gas which makes up more than two thirds of the atmosphere, is brought into the foliage and also to the roots (being moderately soluble in water) in the same ways as is carbonic acid. The nitrogen which, mixed with oxygen, a little carbonic acid, and vapor of water, constitutes the air we breathe, is the source of this fourth plant-element. But it is very doubtful if ordinary plants can use any nitrogen gas directly as food; that is, if they can directly cause it to combine with the other elements so as to form protoplasm. ”

“ The combined nitrogen, which is the product of vegetable and organic life, forms the chief source of nitrogen for the growing plant. 2. Before it is assimilated by the plant, it undergoes a process of oxidation which is due solely to a living organism. 3. The nitrates thus formed are absorbed by the plant, and the albuminoids of the new growth are formed from the nitric nitrogen by a process of reduction. ”

“ The organic nitrogen may be in a form easily nitrified and rendered available for plant food, or it may be inert and resistant to nitrification, as in humus, or exist in an amid state. The ammoniacal nitrogen may exist in small quantities as gaseous ammonia, or be combined with mineral or organic acids. As nitric or nitrous acid the nitrogen will be found combined with bases, or perhaps in minute quantities as 421free acid, in passing under the influence of the nitrifying ferment from the organic to the inorganic state. ”

“ Nitric acid is one of the strongest known, and in solvent power it is excelled by no single acid. The nitrogen contained in crop residues and other organic manures is chiefly in chemical combination with carbon, oxygen and hydrogen, much of it in insoluble protein compounds. Normally this organic nitrogen is transformed in the soil, first into ammonia nitrogen, next into nitrite nitrogen, and lastly into nitrate nitrogen, these three transformations being effected by biochemical action produced by different kinds of living microscopic organisms called bacteria. ”

“ Nitrogen is, as Hood said not so truly about gold, "hard to get and hard to hold." The bacteria that form the nodules on the roots of peas and beans have the power that man has not of utilizing free nitrogen. Instead of this quiet inconspicuous process man has to call upon the lightning when he wants to fix nitrogen. The air contains the oxygen and nitrogen which it is desired to combine to form nitrates but the atoms are paired, like to like. ”

“ Now, vegetables contain nitrogen. They have taken this nitrogen, either directly or indirectly, from the atmosphere and have fixed it in their tissues. Herbivorous animals, in eating vegetables, eat nitrogen, and we, who are carnivorous, we also eat nitrogen, since we eat the herbivorous animals. We also eat vegetable food, many kinds of which contain more or less nitrogen. Do you understand?"
"Yes, I understand," said Miette.
"There is nobody living who really understands this matter very well, for it is an extremely obscure, though very important, subject," replied Monsieur Roger. ”

“ Nitrogen is a substance also generally diffused through nature, and particularly in animal bodies, and causes great changes in those absorbing or exposed to it. This gas, combined with oxygen and hydrogen, produces neither light, heat, nor combustion, but serves to dilute the others: of itself, it is hurtful to animal life. Nitrogen makes the principal part of the salt we call nitre. ”

“ The loss of free nitrogen during the decomposition of nitrogenous organic matter is generally due to oxidizing action. 2. An increase of combined nitrogen in soil may take place by oxidation of free nitrogen to nitric acid. 3. Some organic substances in the presence of a caustic alkali are able to fix free nitrogen without the agency of oxygen, or the formation of nitric acid. ”

“ Nitrogen may be most easily obtained for experiment by setting fire to some phosphorus contained in a porcelain or metallic cup, placed under a gas jar full of air, and resting on the shelf of the pneumatic trough, or in a soup-plate filled with water.
Nitrogen combines in five different proportions with oxygen producing five distinct chemical compounds, named respectively nitrous oxide, nitric oxide, nitric tri-oxide, nitric tetroxide, nitric pent-oxide, which last, united with water, forms nitric acid, now called hydric nitrate, as nitrous acid is termed hydric nitrite. ”

“ 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. ”

“ A high nitrogen content coupled with a high solubility is the end to be aimed at; a high nitrogen with a low solubility shows the presence of gun-cotton, and a low nitrogen, together with a low solubility, the presence of unnitrated cotton. Where complete solubility is essential and the percentage of nitrogen less important, Dr Lunge recommends nitration with a mixture of equal parts of sulphuric and nitric acids containing from 19 to 20 per cent. ”

“ 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. ”

“ Of the adequate resources, nitrogen is needed by the largest number of living bodies and used in the largest quantities. It enters into most animal tissues and the more complex of the vegetable products; being two and a half parts in a hundred of the body of man, or eight per cent, of its solids. It is obtained for the organic world solely by the plants, and obtained only from combinations of nitrogen, the ammonia and nitrates of the air and the soil. ”

“ The supply of oxygen for the formation of nitrates in the soil comes from the air, which consists of about twenty percent oxygen, seventy-eight percent nitrogen, and two percent of other elements and compounds, as argon, carbon dioxid, CO2, water vapor, H2O, etc. One of the important effects of cultivation, or tillage, is that it permits the air more freely to enter the soil, and thus promotes nitrification. ”

“ We observe that the relative proportions of carbon and nitrogen, stand in a fixed relation to the surface of the leaves. Those plants, in which all the nitrogen may be said to be concentrated in the seeds, as the cerealia, contain on the whole less nitrogen than the leguminous plants, peas, and clover.
2. The produce of nitrogen on a meadow which receives no nitrogenised manure, is greater than that of a field of wheat which has been manured. ”

“ It is not probable, however, that the difficult task of oxidizing atmospheric or free nitrogen would be accomplished in nature in only one way. In fact it has already been established that organisms do exist which are capable of oxidizing free nitrogen in a manner wholly independent of other plant life and to produce weighable quantities of nitric acid when developed in media of mineral matters and pure carbohydrates to which free nitrogen has access. ”

“ 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. ”

“ One of the chief elements employed in the formation of these weakly-combined substances is nitrogen—its compounds being designated as nitrogenous substances, and noted, as a class, for the facility with which they are decomposed. Nitrogen is, in fact, the great weak-holder of nature. ”

“ Upon such occasions, the severity of our disappointment will always be in proportion to the importance of the object we desire to accomplish; and it is impossible not to feel that the discovery of the true nature of nitrogen would lead to new views in chemistry, the extent of which it is not easy even to imagine.
The principal objects of research which this paper embraces are,—the elementary matter of ammonia; the nature of phosphorus, sulphur, charcoal, and the diamond; and the constituents of the boracic, fluoric, and muriatic acids. ”

“ Nitrogen, itself, is an inert gas of no particular use, but nitrogenous compounds are necessary to agriculture, to refrigeration, to munitions manufacture, and to the applications of chemistry in general. In the native gaseous state, it makes up about four-fifths of the atmosphere, and combined it occurs as nitrate minerals, as organic compounds, and in carboniferous deposits. ”

“ If a luxuriant growth of stalk and foliage is wanted rather than flowers or fruit, an application of nitrogen alone is usually advisable. The most readily available nitrogen in commercial form is that which is afforded by nitrate of soda and sulfate of ammonia. ”

“ Active Soil Nitrogen.—The material proposed for reducing the nitrates to ammonia, and at the same time to bring ammonia salts and organic nitrogen into a condition for separation by distillation, is sodium amalgam. ”

“ In the urine and in the solid excrements of animals we carry ammonia, and, consequently, nitrogen, to our cultivated plants, and this nitrogen is accompanied by all the mineral elements of food exactly in the same proportions, in which both are contained in the plants which served as food to the animals, or what is the same, in those proportions in which both can serve as nourishment to a new generation of plants, to which both are essential. ”

“ Of late years the industry has gone even further than this, in that a process has been discovered whereby the nitrogen of the air is harnessed, and the product reduced to such forms that it supplies available nitrogen for plant food. ”