Nitrate

“ 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. ”

“ The wet refining process is more tedious and expensive, and is only exceptionally employed, as in the case of preparing the pure metal or its salts for pharmaceutical or chemical purposes. The basic nitrate is the salt generally prepared, and, in general outline, the process consists in dissolving the metal in nitric acid, adding water to the solution, boiling the precipitated basic nitrate with an alkali to remove the arsenic and lead, dissolving the residue in nitric acid, and reprecipitating as basic nitrate with water. ”

“ II.—Calcium nitrate, ammonium nitrate, potassium sulphate, magnesium phosphate, iron chloride (or sulphate) (sodium silicate) .
It is well known that in nature nitrates are formed wherever decomposition of organic nitrogenous substances takes place in the air, the ammonia formed by the decomposition being oxidized to nitric acid. These conditions for the formation of nitrates are present in nearly every cornfield, and they are also the cause of the presence of nitrates in water that has its source near stables, etc. ”

“ The nitrogen in decaying roots, in the dead stems and leaves of plants, and in humus generally is sooner or later changed into a nitrate, the change being effected by bacteria. That
the action of living organisms is the cause of the production of nitrates is supported by the fact that the change does not occur when the soil is heated nor when it is treated with disinfectants which destroy or check the growth and life of bacteria. The process resulting in the formation of nitrates in the soil is spoken of as nitrification. ”

“ Percentage of Nitrogen in Chile Saltpeter.—Chemically pure sodium nitrate contains 16.49 per cent of nitrogen. The salt of commerce is never pure. It contains moisture, potash, magnesia, lime, sulfur, chlorin, iodin, silica and insoluble materials, and traces of other bodies. The value of the salt depends, therefore, not only on the market value of nitrogen at the time of sale, but also on its content of nitrogen. The nitrate of commerce varies greatly in its nitrogen content and is sold on a guaranty of its purity. The best grades range in nitrogen from fifteen to sixteen per cent. ”

“ The thorium nitrate is made up with distilled water to a solution of 25-35 per cent. strength, and the calculated quantity of a standard solution of cerium nitrate is added. It is usual to add to the mixture a small quantity of another nitrate, which on ignition will leave an oxide of which the function is to strengthen the skeleton of ash. Beryllium, zirconium, magnesium, or aluminium nitrate is usually employed, in quantity calculated to leave an amount of oxide constituting about 0·5 per cent. ”

“ These nitrifying germs attack the humus, break it down, separate the nitrogen, cause it to unite with the oxygen of the air and thus build it into nitric acid which can be used by plant roots. This nitric acid if not immediately used will unite with lime or potash or soda or other similar substances and form nitrates, as nitrate of lime, nitrate of potash or common saltpetre. These nitrates are soluble in water and can be easily used by plant roots. If there are no plant roots to use them they are easily lost by being washed out of the soil. ”

“ During the decay of organic matter in the soil, it aids and promotes the production of nitric acid,—so influential, as I believe, in the general vegetation of the globe (see page 35) . With this acid it combines and forms nitrate of lime—a substance very soluble in water—entering readily, therefore, into the roots of plants, and producing upon their growth effects precisely similar to [Pg 198] those of the now well known nitrate of soda. ”

“ We have learned that the air is composed chiefly of oxygen and nitrogen. These are not combined as oxygen and hydrogen are in water, but are simply mixed together, four-fifths of the mixture being nitrogen. Nitrogen is also found in combination in a large number of substances in nature. It is found in the nitrates, as salt-peter or potassium nitrate, KNO3, and Chili salt-peter or sodium nitrate, NaNO3. It is also found in the form of ammonia, which is a compound of nitrogen and hydrogen of the formula NH3, and exists in that form in a limited quantity of the air. ”

“ Walter Crum [5] describes a method of analysing bodies containing nitric acid, applicable to the nitro-compounds; when nitrate of potash is used, it is previously purified by crystallization, and fused at little more than its melting heat. Nitro-Glycerin, gun-cotton, etc., must be deprived of moisture.
A glass jar eight inches long and an inch and a quarter in diameter, is filled with and inverted over mercury; a single lump of time fused nitrate, weighing about six grains, is let up through the mercury into the inverted jar, and afterwards fifty grains of water. ”

“ Schloesing’s Apparatus for Nitric Acid.
Another and more rapid method for dissolving the nitrate, may also be practiced. In a flask holding about one liter, place 220 grams of the soil and 660 cubic centimeters of distilled water and shake vigorously, or enough water to make 660 cubic centimeters together with the moisture remaining in the air-dried sample taken. All the nitrates pass into solution. Throw the contents of the flask into a filter and take 600 cubic centimeters of the filtrate which will contain all the nitrates in 200 grams of the sample taken. ”

“ The chief functions of sodium nitrate are to give to the plant a supply of oxidized nitrogen ready for absorption into its tissues and incidentally to aid, by the residual soda, in the decomposition of silt particles containing potash or phosphoric acid and in supplying to the soil salts of a more or less deliquescent nature. ”

“ Small nitrate deposits are also to he found in various other parts of the world, as in the Sahara, in Russian Turkestan, and in Egypt, where nitrate earths occur which contain about 15 per cent, of calcium and sodium nitrates. The earth has long been used locally as a fertilizer, and its use is supposed to be increasing. The source of the nitrates in this region is not known. ”

“ Much of this is, doubtless taken up as nitrate, yet the direct application of nitrate of soda has comparatively little beneficial influence on their growth. The nitric acid is most likely taken up chiefly as nitrate of lime, but probably as nitrate of potash also, and it is significant that the high nitrogen-yielding clover takes up, or at least retains, very little soda. ”

“ Commercial nitrogen is secured chiefly in the form of animal refuse, as blood and tankage, and in nitrate of soda. It is more likely to be lost by leaching through the land than the mineral substances are, especially if the land lacks humus. Nitrate of soda is very soluble, and should be applied in small quantities at intervals. ”

“ It is afterwards ground into a fine powder and sifted as in the case of the charcoal.
Potassium nitrate is eminently suitable as an oxygen-provider, not being deliquescent. Nitrates are continually being produced in surface soils, &c., by the oxidation of nitrogenous substances. Nitric and nitrous acids are also produced by electric discharges through the atmosphere, and these are found eventually as nitrates in soils, &c. Nitre is soluble in water, and much more so in hot than in cold. Crude nitre, obtained from soils or other sources, is purified by recrystallization. ”

“ 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. ”

“ All these explosives are made from nitric acid and this used to be made from nitrates such as potassium nitrate or saltpeter. But nitrates are rarely found in large quantities. Napoleon and Lee had a hard time to scrape up enough saltpeter from the compost heaps, cellars and caves for their gunpowder, and they did not use as much nitrogen in a whole campaign as was freed in a few days' cannonading on the Somme. Now there is one place in the world—and so far as we know one only—where nitrates are to be found abundantly. ”

“ In all, four nitrate plants were constructed or started, and work upon them was rushed as fast as the supply of labor and materials made possible, while extensions and additions were made to existing facilities. Many scientists and technologists constantly carried on experimental and research work upon processes for the fixation of atmospheric nitrogen and other problems connected with the supply of nitrates, and always with the aim in view of developing methods that would have economic as well as military value. ”

“ The commonly accepted notion that nitrate of soda is a manure which should be reserved for use during the later period of the growth of the bine appears to be erroneous. The summer months, when the growth of the bine is most active, are the months in which natural nitrification is going on in the soil, converting soil nitrogen and the nitrogen of dung, guano, fish, rape dust, shoddy or other fertilizers into nitrates, and placing this nitrogen at the disposal of the plants ”

“ If we can get at any rate a considerable proportion of our nitrate of soda well incorporated with the soil by the time the bine begins its active and rapid growth, we may be helping to lay the foundation of a good crop better than if we delay the application of the nitrate until those months when the soil is actively producing nitrates from other sources. ”

“ 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. ”

“ 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. ”

“ Yet there are many chemists who get good results, and place considerable faith in its accuracy. This can only be due to differences in the manner of working. It is generally understood that nitric acid or nitrates must be absent; and our experience fully confirms this. Precipitations in nitrate solutions are worthless, as the following experiments show. In each experiment the bulk of the solution was 150 c.c. The solutions contained 10 grams of nitre, were freely acid with hydrochloric acid, and were precipitated (while boiling) with slight excess of baric chloride. ”

“ But during spring or fall when lowered soil temperatures retard decomposition, rhizobia can manufacture from 80 to 200 pounds of nitrates per acre. Peas, clovers, alfalfa, vetches, and fava beans can all make significant contributions of nitrate nitrogen and smart farmers prefer to grow their nitrogen by green manuring legumes. Wise farmers also know that this nitrate, though produced in root nodules, is used by legumes to grow leaf and stem. ”

“ Put on a thin layer of nitre, and rather more than half fill the crucible with a mixture of equal parts of soda and nitre. Heat quickly in the blow-pipe flame, and when the mass is fused and effervescing, withdraw and allow to cool. Boil out with water, filter and wash. Insert a piece of litmus paper and cautiously neutralise with nitric acid, using ammonia to neutralise any accidental excess of the acid. Add a gram or so of ammonium nitrate and silver nitrate in excess, neutralise again with ammonia and add two or three grams of sodium acetate. Filter off the precipitate, wash and titrate. ”

“ It strongly rotates the plane of polarization to the right, and forms crystalline salts of which the nitrate is that chiefly used in medicine. The nitrate and phosphate are insoluble in ether, chloroform and benzol, while the hydrochlorate and hydrobromate dissolve both in these menstrua and in water and alcohol; the sulphate and acetate being deliquescent are not employed medicinally. ”

“ The parts of nitrogen obtained, in the form of nitrates, nitrites, and ammonia, less .032 part of 100,000 for that portion in rain, is that nitrogen derived from animal matter. Animal matters dissolved in water, such as those contained in sewage, the contents of privies and cess-pools, or farm-yard manure, undergo oxidation in lakes, rivers and streams very slowly, but, in the pores of an open soil, very rapidly. When this oxidation is complete, they are resolved into mineral compounds; their carbon is converted into carbonic acid; and their hydrogen into water ”