Sodium sulfite

“ There is one substance which will produce that yellow light; it is a curious metal called sodium—a metal so soft that you can cut it with a knife, and so light that it will float on water; while, still more strange, it actually takes fire the moment it is dropped on the water. It is only in a chemical laboratory that you will be likely to meet with the actual metallic sodium, yet in other forms the [pg 326] substance is one of the most abundant in nature. Indeed, common salt is nothing but sodium closely united with a most poisonous gas, a few respirations of which would kill you. ”

“ The mixture at first melts in the solution of the sulphate and sulphuric acid formed by the heat of combination; as heating is continued it gradually becomes solid and finally very hard; it has become gray in color. When it is perfectly 14 dry a test is made to see if it dissolves in sodium hydroxide giving a clear solution. If so, sulphonation is complete. By using an oven with a glass door the reaction mixture can be watched and the completion of the baking observed. However the test for complete solubility should always be made. ”

“ Such distinctions between the elements, according to their power of giving one or several saline forms, is a radical property of no less importance than the basic or acid properties of their oxides. Sodium as a typical metal does not form any acid oxides, whilst chlorine, as a typical non-metal, does not form bases with oxygen. Therefore sodium as an element may be thus characterised: it forms one very stable salt-forming oxide, Na2O, having powerful basic properties, and its salts are of the general formula, NaX, therefore in its compounds it is, like hydrogen, a basic and univalent element. ”

“ Thus sodium sulphate may be formed from sodium oxide and sulphuric anhydride, by oxidising sodium sulphide, Na2S, or sodium sulphite, Na2SO3, &c. When sodium chloride is heated in a mixture of the vapours of water, air, and sulphurous anhydride, sodium sulphate is formed. According to this method (patented by Hargreaves and Robinson) , sodium sulphate, Na2SO4, is obtained from NaCl without the preliminary manufacture of H2SO4. Lumps of NaCl pressed into bricks are loosely packed into a cylinder and subjected, at a red heat, to the action of steam, air and SO2. ”

“ The reactions of decomposition of sodium sulphate are above all noticeable by the separation of oxygen. Sodium sulphate by itself is very stable, and it is only at a temperature sufficient to melt iron that it is possible to separate the elements SO3 from it, and then only partially. However, the oxygen may be separated from sodium sulphate, as from all other sulphates, by means of many substances which are able to combine with oxygen, such as charcoal and sulphur, but hydrogen is not able to produce this action. ”

“ 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. ”

“ If it be heated in oxygen gas in excess, it burns, and is converted into the peroxide of sodium, which, when mixed with combustible bodies, and exposed to the action of heat, deflagrates with violence, giving off its excess of oxygen, and becoming changed into soda, or protoxide of sodium.
Experiment 64. When sulphuret of sodium is mixed with chlorate of potassa, and struck with a hammer, a detonation will ensue; and when sodium is heated nearly to fusion, in contact with sulphuretted hydrogen gas, it will unite with the sulphur; flame will be produced, and hydrogen gas set at liberty. ”

“ Since the constant for the secondary ionization of hydrogen sulphide shows that HS− is an exceedingly weak acid, its salts, Me2S, are very largely hydrolyzed, the constant for water being somewhat greater400 than its own. According to Knox, in a 0.1 molar solution of Na2S about 99% of the sulphide is hydrolyzed: Na2S + H2O ⥂ NaSH + NaOH. In spite of this almost complete hydrolysis, sufficient sodium sulphide remains in a solution of this [p202] substance, to yield a concentration of the sulphide-ion that is far greater than that obtained from a solution of hydrogen sulphide. ”

“ A German chemist named Fleck has discovered that when a warm solution of hyposulphite of soda is added to a double salt of mercury, such as chloride of mercury and sodium, the solution becomes acid, and black sulphide of mercury is deposited. But if the hyposulphite solution is added in excess, and the temperature is not allowed to rise beyond 140° F., the solution remains neutral, and red sulphide of mercury, or vermilion, is deposited. The least quantity of acid causes the production of the black sulphide. The presence of a salt of zinc facilitates the production of the vermilion. ”

“ Sulphates may be detected by heating the salt mixed with sodium carbonate on charcoal in the reducing flame of the blowpipe; sodium sulphide is thus formed, and may be identified by the black stain produced if the mass be transferred to a silver coin and then moistened. In solution. sulphates are always detected and estimated by the formation of a white precipitate of barium sulphate, insoluble in water and all the common reagents. Manufacture.-The first step in its manufacture is the combustion of sulphur. ”

“ The solubility of potassium sulphate does not show the same peculiarities as that of sodium sulphate, because it does not combine with water of crystallisation; at the ordinary temperature 100 parts of water dissolve about 10 parts of the salt, at 0° 8·3 parts, and at 100° about 26 parts. The acid sulphate, KHSO4, obtained easily by heating crystals of the normal salt with sulphuric acid, is frequently employed in chemical practice. On heating the mixture of acid and salt, fumes of sulphuric acid are at first given off; when they cease to be evolved, the acid salt is contained in the residue. ”

“ With oxygen it forms two oxides; with chlorine, a chloride (common salt) ; and—with bromine, iodine, fluorine, &c., bromide, iodide, fluoride, &c., all of which may be obtained by similar processes to the respective compounds of potassium, which, for the most part they resemble.
Uses. Until recently sodium has been regarded as a mere mechanical or philosophical curiosity; it has now, however, become of great practical importance, from being employed in the manufacture of the metals aluminium, magnesium, &c. ”

“ Metallic sulphides when fused with an excess of nitre are completely oxidised. If the ore is rich in sulphur, some inert body (such as sodium chloride, or, better, sodium carbonate) is added to dilute the action. With pure sulphur, the action is so energetic as to cause an explosion, so that care should be taken. With burnt ores (incompletely calcined pyrites) , there is sufficient oxide of iron present to prevent too rapid action. ”

“ It is prepared on the industrial scale for the manufacture of sulphuric acid, for the preparation of sodium sulphate by the Hargreaves process, and for use as a bleaching-disinfecting agent and as a preservative. When compressed it is also used largely as a refrigerating agent, and in virtue of its property of neither burning nor supporting combustion it is also used as a fire extinct or. The solution of the gas in water is used under the name of sulphurous acid. The free acid has not been isolated, since on evaporation the solution gradually loses sulphur dioxide. ”

“ The sulphide of sodium that is sometimes used in tanning may supply a part of the sulphur that is complained of in modern libraries. A second cause is the practice of using split skins, which gives a binding only half as strong and lasting as the old whole skins; and a third cause may be found in the gases escaping from the hot-air furnaces with which libraries are warmed, which are hardly less destructive than the products of illumination, and are more constantly in action. ”

“ Again, the greenish-yellow and intensely poisonous gas, chlorine, unites in definite proportions by weight with the soft, wax-like, and highly poisonous metal sodium to produce the white crystalline solid chloride of sodium (common salt) , a compound which, except in very large quantities, is not only not poisonous, but actually beneficial to health.
Such combinations are called chemical compounds, and the force which binds their constituents together is distinguished from all other attractive forces by the term affinity or chemical affinity. ”

“ Sodium is a soft silver-white metal, scarcely solid at common temperatures, fuses at 194° Fahr., and volatilises at a red heat; it oxidises very rapidly in the air; when placed on the surface of cold water, it decomposes that liquid with great violence, but generally without flame, in which it differs from potassium; on hot water it burns with a bright yellow flame—in both cases a solution of pure soda being formed. Sp. gr. ”

“ When sulphides or mercaptans in glacial acetic acid solution are heated with permanganate, the resulting sulphonic acid compounds exhibit great similarity to compounds containing free carboxyl groups. The sulphonic acid group may also be directly introduced either by concentrated, or by fuming sulphuric acid, or by elimination of halogen by the action of sodium or silver sulphite on the halogen derivatives of the aliphatic compounds. ”

“ Relative Injuriousness of the Several Salts.—Of the three sodium salts that usually constitute the bulk of “alkali,” only the carbonate of soda is susceptible of being materially changed by any agent that can practically be applied to land. So far as we know, the salt of sodium least injurious to ordinary vegetation is the sulfate, commonly called Glauber’s salt, which ordinarily forms the chief ingredient of “white” alkali. ”

“ Sodium is the metallic base of soda. It is silver white with a high lustre; crystallizes in cubes; of the consistence of wax at ordinary temperatures, and completely liquid at 194°, and139 volatilizes at a bright red heat. It is very generally diffused throughout nature though apparently somewhat less abundantly than potassium in the solid crust of the globe.
Salt, the chloride of sodium, a natural compound of one atom of chloride and one of sodium. It occurs as a rock inter-stratified with marl, and sandstones, and gypsum, and as an element of salt springs, sea water, and salt water lakes. ”

“ By sublimation with chloride of sodium, the sulphate of ammonium is converted, by double decomposition, into chloride of ammonium, which sublimes; and sulphate of sodium, which remains in the subliming pot. A similar change occurs when the solution of the sulphate, prior to crystallisation, is decomposed by the addition of chloride of sodium, or any other chloride. When the ‘gas-liquor’ is at once converted into chloride of ammonium by the addition of hydrochloric acid, the sublimation merely purifies the salt. Like changes occur when bone-spirit is employed. ”

“ The crystals fuse at 56°, and lose all their water at 100°. When the dry salt is ignited it gives sodium sulphide and sulphate. With acids, a solution of the thiosulphate soon becomes cloudy and deposits an exceedingly fine powder of sulphur (Note 10) . If the amount of acid added be considerable, it also evolves sulphurous anhydride: H2S2O3 = H2O + S + SO2. Sodium thiosulphate has many practical uses; it is used in photography for dissolving silver chloride and bromide. Its solvent action on silver chloride may be taken advantage of in extracting this metal as chloride from its ores. ”

“ In this way the chance of error from what are termed "accidental causes" is diminished.
The following experiments show the effect of variation in the conditions of titration:—
Make a standard solution of sulphuric acid by diluting 43.65 grams of sulphuric acid (sp. g. 1.6165) to 1 litre: 100 c.c. will contain 1 gram of sulphur. An equivalent solution may be made by dissolving 100.62 grams of sodium sulphate crystals (Na2SO4.10H2O) , or 86.88 grams of ferrous sulphate (FeSO4.7H2O) , in water (oxidising the latter) , and diluting to 1 litre. ”

“ If a solution of sodium sulphate which has been saturated at a temperature of about 34° be cooled down to a temperature below 17°, while care is taken that the solution is protected against access of particles of Glauber's salt, crystals of a second hydrate of sodium sulphate, having the composition Na2SO4,7H2O, separate out. ”

“ Acid sodium sulphate, NaHS04, has been employed in the manufacture of sul hur trioxide. When heated it loses water to form sodium pyrosufphate, Na2S2O7, which on treatment with sulphuric acid yields normal sodium sulphate and sulphur trioxidei The normal sulphates are the more important, and occur widely and abundantly distributed 'in the mineral kingdom; anhydrite, gypsum, angle site, barytes, celestite and kieserite are among the commonest species. As a eneral class, the sulphates are soluble in water, and exhibit well crystallized forms. ”

“ The heating of a charge lasts nine to ten hours; the larger the quantity of sodium sulphide in the mixture the shorter is the time required. The mixture is spread out in the muffles in a layer 7 to 9 centimetres thick, and brought to a moderate red heat. When the whole [Pg 215] mass is uniformly hot it is more strongly heated; the change of the constituents then becomes visible. The mixture takes at first a brownish colour, and is somewhat similar in appearance to liver of sulphur. ”