Nitrogen-containing compound

“ The results under proper conditions are accurate even when a small quantity of nitric nitrogen is present. When, however, there is any considerable quantity of this compound in the sample the method becomes inapplicable by reason of non-reduction of some of the nitrogen oxids produced by the combustion.
In bodies very rich in nitrogen such as urea all the nitrogen is not transformed directly into ammonia at the commencement of the combustion. A portion of it may unite with a part of the carbon to form cyanogen, which may unite with the soda to form sodium cyanid. ”

“ 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 free nitrogen of the air cannot be utilized directly by plants. It must first be converted into some combination with other chemicals, as a solid or liquid, which can be absorbed by the plant. Among others who worked on the problem of fixing atmospheric nitrogen were two German chemists, Doctors Caro and Frank, who found that a compound of calcium and carbon heated to a high temperature would absorb nitrogen and retain it in a form that could be applied to the soil and serve as a food for plants.
Sugar Cane Crop Fertilized with Cyanamid Mixtures. ”

“ 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. ”

“ As regards the first alternative, it must be stated that we know of no source other than the decomposition of plants from which ammonia can be derived, and we are therefore compelled to adopt the second alternative, and to admit that there must be some other source of nitrogen, and it cannot be doubted, from what has been already stated, that it is from nitric acid only that it can be obtained. ”

“ There are certain compounds containing nitrogen which are indispensable to our food. An animal nourished entirely on food which is destitute of nitrogen would become weak and would soon die."
"Excuse me, Monsieur Roger," said Albert Dalize: "how can nitrogen enter into our food?"
"That is a very good question," added Miette, laughing; "surely you cannot eat nitrogen and you cannot eat gas."
"The question is indeed a very sensible one," answered Monsieur Roger; "but this is how nitrogen enters into our food. We are carnivorous, are we not? we eat meat and flesh of animals. ”

“ 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. ”

“ 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. ”

“ There are, in addition, the dead bodies of other soil organisms, such as protozoa and algæ. The relative importance of these sources of nitrogen is not known, but almost certainly varies greatly with the state of activity of the various groups of the soil population. Bacteria are able to utilise organic nitrogen compounds as energy sources, as can be exemplified in the oxidation of a simple amino-acid:—
It will be seen that, in the acquirement of energy from such a compound, ammonia is released as a by-product. ”

“ But it is also possible that some direct oxidation of protein or amino-acids may yield gaseous nitrogen. However it is brought about it affects a considerable proportion of the entire stock of nitrogen, and it becomes more serious as cultivation is intensified. ”

“ 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. ”

“ These decay rapidly when added to the soil and are particularly valuable when applied to light soils, where nitrates or ammonia leach too rapidly and should not be applied until the crops are up and growing. They make available during their processes of fermentation the phosphoric acid and potash already present in the soil. Sulphate of ammonia, containing about twenty per cent. of nitrogen is a valuable chemical form in which to secure nitrogen as it does not leach from the soil as nitrate of soda does and so can be made available by the plant without loss. ”

“ 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. ”

“ The nitrogen gas in solution in rain water has no significance as a plant food. (2) By the action of certain anaerobic organisms herding in the rootlets of leguminous plants, free nitrogen may be oxidized and put into form for assimilation. (3) By the action of certain organisms on nitrogenous compounds pre-existing in the soil, ammonia, nitrous acid, and finally, nitric acid, are produced. It is believed that the plant organism, unaided by the activity of a micro-organism, is unable to assimilate nitrogen unless it be fully oxidized to nitric acid. ”

“ In general, far the largest part of soil nitrogen, excluding the atmosphere diffused in the pores of the soil, is found in the organic state and is derived from the débris of animal and vegetable life and from added fertilizers. As ammonia, the nitrogen can only be regarded as in a transition state, arising from the processes of decay, or incomplete nitrification. As nitric acid, it is found as a completed product of nitrification, or as the result of electrical action. ”

“ This is the general process of nitrification in which the nitrifying bacteria transform or transfer the nitrogen from insoluble organic compounds into soluble compounds in which it may serve as available plant food. The nitrate which is thus formed may be calcium nitrate or magnesium nitrate or potassium nitrate or even sodium nitrate, depending upon which of these alkaline elements is present in the must suitable form. If no alkaline element is present in available form then no nitrates can be made in the soil. ”

“ It is the character of nitrogen to refuse chemical combinations. Uncombined nitrogen is nowhere available for vital uses, to any appreciable extent. Filling perfectly its humble service in Nature as a diluent in the air, its qualification is to be inert and to remain changeless. Among the resources of life and in the marts of subsistence where its compounds rank high in value, nitrogen as a simple has no place at all. ”

“ 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. ”

“ This is most cheaply done by neutralizing the nitric acid with lime or the ammonia with sulfuric acid, yielding calcium nitrate or ammonium sulfate, respectively. Whether the nitrate or the ammonium salt is made the constituent of the fertilizer makes little difference; for, though plants directly assimilate the nitrogen only in the form of nitrate, yet there are always present in soils the so-called nitrifying bacteria, whose function it is to convert ammonium compounds into nitrates. ”

“ 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. ”

“ Besides being nearly four fifths of the air, it forms twenty-two per cent of nitric acid, forty-five per cent of saltpeter or niter, eighty-two per cent of ammonia, and about twenty-five per cent of sal ammoniac. Plants can not use nitrogen in its pure form, but one or another of these forms will be found in the soil, whence it may be extracted. ”

“ A variety of nitrogenous substances have proved susceptible to nitrification in solution. The weight of evidence, however, appears to show that in all cases the nitrogen first assumes the form of ammonia, and that the latter is, strictly speaking, the only substance capable of being nitrified. ”

“ Hence, although this gas is present in the atmosphere surrounding the plant, the147 plant will perish if nitrogen does not exist in some combined form in the soil. Nitrates and compounds of ammonia are widely distributed in nature, and it is from these bodies that the plant obtains, by means of its roots, the necessary nitrogen. ”

“ These fresh, pure organisms had the faculty of converting ammonia into nitrous acid only and not into nitric acid.
With the organisms thus prepared a number of solutions of potassium nitrite containing phosphates and other mineral ingredients were seeded. In no case was any loss of nitrite found, which is proof that the solution contained no organisms capable of oxidizing nitrous acid. The organisms prepared as above, have the power of nitrifying organic substances containing nitrogenous bodies. ”

“ The nitrifying bacteria are those which have the power to form nitrates. In the following brief discussion of this subject we include at least three species of bacteria which by their combined or successive action have the power to transform organic nitrogen into nitrate nitrogen, which is a suitable form of nitrogen for plant food. ”

“ Nascent hydrogen is a powerful reducing agent, and would of itself withdraw the oxygen from nitrates to form nitrites, while hydroxyl in contact with ammonia will cause the formation of water and the liberation of nitrogen. Part of this nitrogen is undoubtedly utilized by the bacteria, and the rest is returned to the air. How the inert nitrogen molecule is torn apart and the nascent nitrogen atoms thus formed utilized by the bacteria for their growth is a question that is more difficult of solution. ”

“ After the organic nitrogen of decomposing substances has been converted into ammonia, and to a small extent into free nitrogen, the latter can at once be utilised by the root-nodule organisms and other bacteria in the soil, but the ammonia must undergo two further changes and combine with a base to form a nitric salt before it is available for plant life. ”

“ 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. ”

“ It is much more probable, however, that it depends on small quantities of ammonia or nitric acid which had not been completely removed from the air by the means employed for that purpose, for nothing is more difficult than the complete abstraction of these substances, and as the gain of nitrogen was only 0·8 grains, while 60,000 gallons of air, and 13 of water, were employed in the experiment, which lasted for a considerable time, it is reasonable to suppose that a sufficient quantity may have remained to produce this trifling increase. ”