Sulfur dioxide

“ The higher and lower oxides of chlorine are powerful oxidising agents, whilst the higher oxide of sulphur, SO3, has but feeble oxidising powers, and the lower oxide, SO2, frequently acts as a reducing agent, and is formed by the direct combustion of sulphur, just as carbonic anhydride, CO2, proceeds from the combustion of carbon. In the combustion of sulphur, and also in the oxidation (roasting) of the sulphides and polysulphides by their ignition in air, sulphurous oxide, or sulphurous anhydride, or sulphur dioxide, SO2, [31 bis] is exclusively formed. ”

“ As it is natural for sulphur to be in the reduced state, and for phosphorus to be in the oxidized state, so it is in the nature of carbon to be related to both states and therefore to oscillate between them. By its readiness to change over from the oxidized to the reduced state, it can serve the plant in the assimilation of light, while by its readiness to make the reverse change it serves man and animal in the breathing process. We breathe in oxygen from the air; the oxygen circulates through the blood-stream and passes out again in conjunction with carbon, as carbon dioxide, when we exhale. ”

“ 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. ”

“ The rare gases of the air especially should originally have come from the exterior parts of the sun, as did the nitrogen.
An atmosphere of such a composition would be utterly unendurable to living beings. It must, if organisms are going to thrive therein, be purified from such poisons as carbon dioxide, gaseous sulphur, cyanogen, and sulphurous acid. We know that such a process has taken place and that the sunlight has been the great chemist who produced oxygen and carbon from the carbon dioxide. ”

“ It will be noticed that in the earlier stages the quantity of sulphur impurities is actually increased between the purifiers—in fact, the greater amount of sulphiding procures the ready removal of the carbon disulphide,—but it is the carbon dioxide in the gas that is the disturbing element, inasmuch as it decomposes the combinations of sulphur and calcium ”

“ Sulphurous Acid, H2SO3.—The reagent used may be regarded as a saturated solution of sulphur dioxide in water. It may be purchased, and keeps for a long time. It may be made by heating copper with sulphuric acid and passing the gas formed into water. The heat should be withdrawn when the gas is coming off freely. It is used as a reducing agent, and should not be diluted.
Sulphuric Acid, H2SO4. (Sp. gr. 1.84, containing 96 per cent. of real acid, H2SO4.) —This acid forms insoluble sulphates with salts of lead, strontium, and barium. ”

“ If the current be so strong that new hydrogen and hydroxyl ions cannot be formed in time, other substances are liberated; in a solution of sulphuric acid a strong current will evolve sulphur dioxide, the more readily as the concentration of the solution is increased. Similar phenomena are seen in the case of a solution of hydrochloric acid. When the solution is weak, hydrogen and oxygen are evolved; but, as the concentration is increased, and the current raised, more and more chlorine is liberated. ”

“ Sulphur dioxide, recognized by its smell and acid reaction, results from the ignition of certain sulphites, sulphates, or a mixture of a sulphate with a sulphide. Nitrogen oxides, recognized by their odour and brown-red colour, result from the decomposition of nitrates. Carbon dioxide, recognized by turning lime-water milky, indicates decomposable carbonates or oxalates. Chlorine, bromine, and iodine, each recognizable by its colour and odour, result from decomposable haloids; iodine forms also a black sublimate. ”

“ This was nothing less than the attempt to free the burner-gases completely from all impurities, so that finally there should remain absolutely nothing but the pure gases, that is, sulfur dioxid, oxygen and nitrogen.
With an enormous expenditure of time, care, money and patience, experiment after experiment was undertaken in the effort to reach this goal, and it may well be said without exaggeration that it has been one of the most difficult problems of modern industry which has had to be solved, in order to render possible the present revolution in the manufacture of sulfuric acid. ”

“ Its usual form of occurrence is in combination with the metals to form sulfids, or with oxygen and a metal to form sulfates. Sulfur and iron combine to form iron pyrites or iron disulfid (FeS2) , while sulfur, oxygen, and calcium are found in gypsum, an important fertilizing compound.
Sulfur plays an important part in the nourishment of plants, being found in them both as sulfuric acid and in organic compounds. Methods for estimating the sulfur in both forms will be found in another part of this manual.
9. Hydrogen is a colorless, invisible gas, without taste or smell. ”

“ Place some sulphur in a little copper ladle attached to a wire, and called a deflagrating spoon, passed through a round piece of zinc or brass plate and cork, so that the latter acts as an adjusting arrangement to fix the wire at any point required. The combustion of the sulphur, previously feeble, now assumes a remarkable intensity, and a peculiar coloured light is generated, whilst the sulphur unites with the oxygen, and forms sulphurous acid gas. It produces, in fact, the same gas which is formed by burning an ordinary sulphur match. ”

“ The main action of sulphuric acid, so long associated with the alkali process, has made enormous strides during the present century, but is still, in the main, the original process of causing sulphur dioxide in presence of water to absorb the oxygen of the air through68 nitric oxide. But the saving of the oxides of nitrogen through the invention of a sulphuric acid power by Gay-Lussac, known by his name, and the re-utilization of these oxides in the “Glover” power, invented by John Glover, of Newcastle, have greatly lessened the cost of the acid. ”

“ Precipitation with sulphur dioxide and sulphuretted hydrogen proceeds much more rapidly, and has been adopted at many works. Sulphur dioxide, generated by burning sulphur, is forced into the solution under pressure, where it interacts with any free chlorine present to form hydrochloric and sulphuric acids. Sulphuretted hydrogen, obtained by treating iron sulphide or a coarse matte with dilute sulphuric acid, is forced in similarly. The gold is precipitated as the sulphide, together with any arsenic, antimony, copper, silver and lead which may be present. ”

“ When the gas had to be purified from carbon disulphide as well as from sulphuretted hydrogen, slaked lime was employed for the removal of carbon dioxide and the greater quantity of the sulphur compounds, whilst a catch box or purifier of oxide of iron served to remove the last traces of sulphuretted hydrogen. ”

“ As a rule more or less sulfur is contained in coal, wood, and other organic matter, and this also is burned to sulfur dioxid and carried into the air, from which it is brought back to the soil in rain in ample amounts to supply all of the sulfur required by plants. ”

“ When sulphur is burned in air or oxygen, sulphur dioxide is produced, which is a powerful disinfectant, used to fumigate rooms which have been occupied by persons suffering from some infectious disease. ”

“ In Germany the coal coked so that the by-products could be recovered was 30 per cent, in 1900; 82 per cent, in 1909.
Our chemists are devising means to prevent the contamination of the atmosphere by industrial wastes. Witness the Sulphur, Copper and Iron Company at Ducktown, Tenn, whose blast furnace gases contain a high percentage of sulphur dioxide because of the abundance of sulphur in the ores. Instead of, as formerly, allowing this to escape to poison the surrounding vegetation it is caught and converted into sulphuric acid. One hundred and sixty tons are produced daily, of high purity ”

“ Improved methods of analysis, which insure that the sulfur which is present in the plant tissue in organic combinations is oxidized under such conditions that it is not lost by volatilization during the combustion of the material, have shown that the total sulfur which is present in many plants approaches the quantity of phosphorus which is present in the same tissue. ”

“ The purity of the product is dependent upon the time of reaction. There is always a slow reaction between the mustard gas and sulfur chloride, and because of this the charge should be completed in 8 hours.
In general the more sulfur that comes out of the solution, the better is the product. Temperature has a marked effect on the separation of sulfur. In order to entirely remove the sulfur from the product it was the custom to increase the temperature at the close of the reaction from 55° to 70° C. This, however, caused plugging of the lines and the reactor. ”

“ Condenses the gas by means of liquid air and fraction ates the product. Sulphuretted hydrogen is a colourless gas possessing an extremely offensive odour. It acts as a strong poison. It burns with a pale blue flame, forming sulphur dioxide and water. It is moderately soluble in water, the solution possessing a faintly acid reaction. This solution is not very stable, since on exposure to air it slowly oxidizes and becomes turbid owing to the gradual precipitation of sulphur. The gas is much more soluble in alcohol. ”

“ The white vapour is the oxygenated sulphur, which assumes the form of an elastic fluid of a pungent and offensive smell, and is a powerful acid. Here you see a chemical combination of oxygen and sulphur, producing a true gas, which would continue such under the pressure and at the temperature of the atmosphere, if it did not unite with the water in the plate, to which it imparts its acid taste, and all its acid properties.—You see, now, with what curious effects the combustion of sulphur is attended. ”

“ The sulphur must unite with one portion of the oxygen to produce sulphurous acid gas, and also with the potassa of the nitre, and form a sulphuret, a compound necessary to be formed, before we can explain the production of sulphuretted hydrogen gas, which results from the decomposition of water contained in the nitre. ”

“ The Common Gases dissolved or imprisoned by well and spring water are carbonic acid, sulpurretted hydrogen and the components of air—oxygen and nitrogen. Of these only one is dangerous—sulpurretted hydrogen—and that is easily detected by its smell, resembling that of spoiled eggs. It gives the characteristic odor to “sulphur” waters. Carbonic acid and air give to waters their sparkling quality—the former being often artificially introduced, as in “soda-water,” &c.
The Organic Matter in well, spring, and river water may be dead or living, and we will consider the two classes separately. ”

“ The solid sulphur could not catch fire. Therefore the heat of my tinder during the interval that I was coaxing the match (as I called it) was being exerted in converting my solid into gaseous sulphur. When the solid sulphur had had sufficient heat applied to it to vapourize it, the sulphur gas immediately caught fire. Now understand, that in order to convert a solid into a liquid, or a liquid into a gas, heat is always a necessity. I must have heat to produce a gas out of a solid or a liquid. I will endeavour to make this clear to you by an experiment. ”

“ Na2SO4 + H2SO4 = 2NaHSO4.
Acid sulphites and sulphides may be made in the same ways.
Carbon disulphide (CS2) . When sulphur vapor is passed over highly heated carbon the two elements combine, forming carbon disulphide (CS2) , just as oxygen and carbon unite to form carbon dioxide (CO2) . The substance is a heavy, colorless liquid, possessing, when pure, a pleasant ethereal odor. ”

“ For the successful operation of acid-making plant, as at present developed, it is necessary that the proportions of sulphur dioxide in the gases shall not fall below a certain minimum, and further, that the gases shall not contain more than certain limiting proportions of other interfering constituents, such as, for instance, CO2. ”

“ The reaction between sulphide of iron and sulphuric acid takes place at the ordinary temperature, and is accompanied by just as small a development of heat as in the liberation of hydrogen itself, FeS + H2SO4 = FeSO4 + H2S. [15]
In nature sulphuretted hydrogen is formed in many ways. The most usual mode of its formation is by the decomposition of albuminous substances containing sulphur, as mentioned above. Another method is by the reducing action of organic matter on sulphates, and by the action of water and carbonic acid on the sulphides formed by this reduction. ”

“ It burns with a pale blue flame to form carbon dioxide and sulphur dioxide. It is almost insoluble in water, but mixes in all proportions with absolute alcohol, ether, benzene and various oils. It is a good solvent for sulphur, phosphorus, wax, iodine, &c. It dissociates when heated to a sufficiently high temperature. A mixture of carbon bisulphide vapour and nitric oxide burns with a very intense blue-coloured flame, which is very rich in the violet or actinic rays. When heated with water in a sealed tube to 150° C. it yields carbon dioxide and sulphuretted hydrogen. ”

“ The nitrous gases employed in the ordinary chamber process of manufacturing sulphuric acid also act catalytically. Mention may be made of the part played by water vapour in conditioning many chemical reactions. Thus sodium will not react with dry chlorine or dry oxygen; carbon, sulphur and phosphorus will not burn in perfectly dry oxygen, neither does nitric oxide give red fumes of the peroxide. ”