Potassium nitrate

“ 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. ”

“ Potassium sulphide (K2S) is a solid substance, and it is largely due to it that gunpowder gives off smoke and soot when it explodes. Smokeless powder consists of organic substances which, on explosion, give only colorless gases, and hence produce no smoke. Sodium nitrate is cheaper than potassium nitrate, but it is not adapted to the manufacture of the best grades of powder, since it is somewhat deliquescent and does not give up its oxygen so readily as does potassium nitrate. ”

“ The nitrates of the metals, on heating, leave the oxide of the metal. It is as yielders of oxygen that nitrates are so largely used in the manufacture of explosives. Gunpowder contains from 65 to 75 per cent. of potassium nitrate (nitre) .
Nitrates are best detected and determined by their yielding nitric oxide when treated with sulphuric acid and a suitable reducing agent, such as ferrous sulphate, mercury, or copper. Nitric oxide is a colourless gas very slightly soluble in water. ”

“ The iron glows brightly and burns to oxide, the saltpetre changes to potassium nitrite. The mass is dissolved in a little hot water, the solution filtered and cooled, when most of the undecomposed saltpetre crystallises out, whilst the nitrite remains in solution. After further evaporation and separation of another crop of potassium nitrate crystals, the solution can be used to precipitate the aureolin. ”

“ 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. ”

“ Potassium nitrate, or common nitre or saltpetre, KNO3, is chiefly used as a component part of gunpowder, in which it cannot be replaced by the sodium salt, because the latter is deliquescent. It is necessary that the nitre in gunpowder should be perfectly pure, as even small traces of sodium, magnesium, and calcium salts, especially chlorides, render the nitre and the gunpowder capable of attracting moisture. Nitre may easily be obtained pure, owing to its great disposition to form crystals both large and small, which aids its separation from other salts. ”

“ Potassic nitrate has been taken with fatal result by man; the poisonous nature of sodic nitrate is established by experiments on animals. The action of the nitrates of the alkalies is separated from that of the other neutral salts of potassium, &c., because in this case the toxic action of the combined nitric acid plays no insignificant part. Large doses, 3-5 grms. (46·3-77·2 grains) , of potassic nitrate cause considerable uneasiness in the stomach and bowels; the digestion is disturbed; there may be vomiting and diarrhœa, and there is generally present a desire to urinate frequently. ”

“ The solution of potassium nitrate (b) is best prepared from a stronger one (a) containing 0.0001 gram nitrogen to the cubic centimeter, or 0.7214 gram potassium nitrate to the liter; 100 cubic centimeters of (a) made up to one liter give the solution (b) . It is obvious that the series of solutions, above described, could be made directly from (a) , but by first making (b) , greater accuracy is secured.
5. For purposes which will be presently described, a solution of aluminum sulfate is required, containing five grams to the liter. The salt used must be free from chlorin and iron ”

“ The undissolved portion, which consists of wood-pulp, potassium nitrate, and other salts, is filtered off through a linen or paper filter, dried and weighed.
~Solution.~—The ether-alcohol solution contains the nitro-cotton and the nitro-glycerine in solution. [A] To this solution add excess of chloroform (about 100 c.c. will be required) , when the nitro-cellulose will be precipitated in a gelatinous form. This should be filtered off through a linen filter, and allowed to drain. It is useless to attempt to use a filter pump, as it generally causes it to set solid. ”

“ 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. ”

“ Ten, divided by the number of c.c. of water used, expresses the milligramme equivalents of nitric acid per litre; thus, if 4 c.c. of water are used, there are 2·5 milligramme equivalents of nitric acid, equal to 252·5 milligrammes of potassium nitrate per litre. If a preliminary test with brucine has shown that the water contains very little nitric acid, 2 c.c. only of the indigo solution must be used, or sometimes as little as 1 c.c. If more than 8 c.c. of water is required to destroy the blue colour, 100 c.c. ”

“ In a diluted state it is detected by its acid reaction; by no precipitate being obtained by nitrate of barium or by nitrate of silver, proving the absence of sulphuric and hydrochloric acids; further, by neutralizing the liquid with potass, evaporating it, and then procuring crystals of [Pg 39] nitrate of potassium, in the form of lengthened fluted prisms, which are permanent in the air. These crystals may be powdered and moistened with strong sulphuric acid, when a colorless acid vapor (nitric acid) will be evolved. ”

“ On oxidation it yields nitro-urethane. With a methyl alcoholic solution of potash it yields a yellow precipitate, which is probably the potassium salt of nitrosocarbamic acid, NK·NO·CO2K. Nitrourethane, NO2·NH·CO2C2H5, formed by dissolving urethane in concentrated sulphuric acid and adding ethyl nitrate to the well-cooled mixture (J. Thiele, ibid.) ”

“ Nitrate of lead offers no advantages over the acetate, and is generally more expensive to use. Free nitric acid is more objectionable than free acetic acid, because it may act as a solvent on chrome yellow and liberate free chromic acid, which is liable to “turn” the yellow. When using lead nitrate it is preferable to neutralise potassium bichromate with soda, to avoid the presence of free nitric acid. ”

“ Diamond through your valuable publication, that I am, in common with many others, extremely indebted to him for his collodion, and would esteem it a favour if he would answer the following Queries, viz.:
1st. He says, in answer to a previous Query, that "nitrate of potassa" is not formed in his process. Now I wish to ask if (as the iodide of silver is redissolved in iodide of potassium) it is not formed when the plate is plunged into the nitrate silver bath, as the nitrate decomposes the iodide of potassium? ”

“ Why does the caustic condition of the solution require a larger dose of nitrate of silver, and does not this larger quantity of nitrate of silver more than outbalance the difference between the new process and the old, as regards price? I pay 1s. 3d. for an ounce of iodide of potassium of purest quality; the commoner commercial quality is cheaper. ”

“ For making these, some sulpho-cyanide of potassium is poured into a solution of nitrate acid on mercury, which forms a precipitate of sulpho-cyanide of mercury. This is a white, combustible powder, which after passing through a filter, should be transformed into a stiff pulp by means of water containing a solution of gum. The pulp is afterwards mixed with a small quantity of nitrate of potash, and fashioned into cones or cylinders of about an inch and a quarter in length, which should be thoroughly dried. ”

“ It is rapidly acted on by nitric acid, with formation of the nitrate. Pure water put into a leaden vessel and exposed to the air soon corrodes it, and dissolves the newly formed oxide; but river and spring water have little action upon lead, provided there is no free carbonic acid present, the carbonates and sulphates in such water destroying their solvent powers. It has been found that a very small amount of phosphate of sodium or of iodide of950 potassium, dissolved in distilled water, prevents its corrosive action on this metal. ”

“ A solution of nitrate of potash, when treated with a zinc couple (see “Foods,” p. 566) , is decomposed, the nitrate being first reduced to nitrite, as shown by its striking a red colour with metaphenylene-diamine, and then the nitrite farther decomposing, and ammonia appearing in the liquid. If the solution is alkalised, and treated with aluminium foil, hydrogen is evolved, and the same effect produced. As with all nitrates, potassic nitrate, on being heated in a test-tube with a little water, some copper filings, and sulphuric acid, evolves red fumes of nitric peroxide. ”

“ The first product of the reaction is nitric oxide, which on cooling with the residual gases produces nitrogen peroxide. The cooled gases are then led into towers where they meet a stream of water coming in the contrary direction. Nitric acid (up to 59%) is formed in the first tower, and weaker acids in the successive ones; the last tower contains milk of lime which combines with the gases to form calcium nitrite and nitrate (this product, being unsuitable as a manure, is decomposed with the acid, and the evolved gases sent back) . ”

“ Animal substances furnish azote, as it is one of their constituent parts; and in the act of its separation, by uniting with oxygen, principally furnished by the air, it forms nitric acid; which, attaching itself to the alkali of the vegetable matter, or the lime usually added to nitre beds, or to other salifiable bases, forms either nitrate of potassa, nitrate of lime, or a nitrate of the particular base. The lixiviation of the nitrous substances, and the use of wood ashes, or potash itself, will produce saltpetre. ”

“ The presence of Nitric Acid may be discovered by saturating the suspected sample with pure potass, evaporating to dryness, and then treating the product with a highly concentrated alcohol, the acetate of potass will be thus dissolved, but as it exerts no action on the Nitrate it will be found in the residuum, and may be recognised by its deflagration, when thrown upon burning charcoal; [332] Copper may be detected by the acid assuming a blue colour, when supersaturated with ammonia; and Lead, by a solution of sulphuretted hydrogen, producing a dark coloured precipitate. ”

“ It deserves also to be remembered, that a table of chemical affinity will not upon all occasions prove to the medical practitioner an unerring pilot; in those cases for instance, where a super or sub Salt is readily formed, a substance less weakly attracted by another than a third, will sometimes precipitate this third from its combination with the second, thus in the production of Nitric acid, we decompose the Nitrate of Potass by virtue of the superior affinity of the Sulphuric acid for its base, the nitric acid is accordingly disengaged, and a Sulphate of Potass remains in the retort ”

“ 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. ”

“ In one pot, he put common salt and oil of vitriol; in another pot, animal matter. Being conducted by pipes into the chamber, the gases united, and sal ammoniac was formed. Other improvements have been made, as obtaining ammonia from coal soot, &c.
Ammonia is generated in artificial nitre beds, and is at first united with nitric acid; which compound is subsequently decomposed, as the process of putrefaction goes on, by the potassa, calcareous earth, &c. present in nitre beds. See Nitrate of Potassa. ”

“ Nitrous acid, HNO2, is found to some extent in the form of its salts in the atmosphere and in rain water. The pure acid has not yet been obtained, since in the presence of water it decomposes with formation of nitric acid and liberation of nitric oxide: 3HNO2 =HNO3+2NO+H2O. Its salts may be obtained in some cases by heating the corresponding nitrates, but the method does not give good results. Sodium nitrite, the most commonly used salt of the acid, is generally obtained by heating the nitrate with metallic lead ”

“ Nitre contains nearly 48% of oxygen by weight, five-sixths of which is available for combustion purposes. Nearly all the gases of the powder explosion are derived from the nitre. The specific gravity of nitre is 2.2 : 200 grams will therefore occupy about 100 cubic centimetres volume. This quantity on its decomposition by heat alone yields 28 grams or 22,400 c.c. of nitrogen, and 80 grams or 56,000 c.c. of oxygen as gases, and 94 grams of potassium oxide, a fusible solid which vaporizes at a very high temperature. ”