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PHOSPHORUS (Gr. 4ws, light, sPEpety, ...
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See also:PHOSPHORUS (Gr. 4ws, See also:light, sPEpety, to See also:bear) , the name originally given to any substance which possessed the See also:property of See also:phosphorescence (q.v.), i.e. the See also:power of shining in the dark, but now generally restricted to a non-metallic See also:element, which was first known as Phosphorus mirabilis or igneus. This element is very widely distributed in nature in See also:combination, but is never found See also:free. In the See also:mineral See also:kingdom it is exceptionally abundant, forming large deposits of See also:phosphates (q.v.). It is also necessary to See also:animal and See also:vegetable See also:life (see MANURE). It occurs in the urine, See also:blood, tissues, and bones of animals, See also:calcium phosphate forming about 58% of bones, which owe their rigidity to its presence. The element appears to have been first obtained in 1669 by See also:Brand of See also:Hamburg; See also:Krafft bought his See also:secret and in 1677 exhibited specimens in See also:England, where it created an immense sensation. Its preparation was assiduously sought for, and Kunckel in 1678 and See also:Boyle in 168o succeeded in obtaining it by the same See also:process as was discovered by Brand, i.e. by evaporating urine to dryness and distilling the See also:residue with See also:sand. This method was generally adopted until 1775, when See also:Scheele prepared it from bones, which had been shown by Gahn in 1769 to contain calcium phosphate. Scheele treated See also:bone ash with nitric See also:acid, precipitated the calcium as sulphate, filtered, evaporated and distilled the residue with See also:charcoal. See also:Nicolas and Pelletier improved the process by decomposing the bone-ash directly with sulphuric acid; whilst See also:Fourcroy and See also:Vauquelin introduced further economies. In See also:modern practice degreased bones (see See also:GELATIN), or bone-ash which has lost its virtue as a filtering See also:medium, &c., or a mineral phosphate is treated with sufficient sulphuric acid to precipitate all the calcium, the calcium sulphate filtered off, and the filtrate concentrated, mixed with charcoal, See also:coke or sawdust and dried in a muffle See also:furnace. The product is then distilled from See also:Stourbridge See also:clay retorts, arranged in a See also:galley furnace, previously heated to a red See also:heat. The temperature is now raised to a See also: One of the See also:special advantages of the See also:electrical over the older process is that the distilling vessels have a longer life, owing to the fact that they are not externally heated, and so subjected to a relatively high temperature when in contact with the corrosive slag formed in the process. The Readman-See also:Parker process (see Jour. See also:Soc. Chem. Ind., 1891, x. 445) appears to be very generally adopted. Readman, experimenting with a Cowles furnace in See also:Staffordshire in 1888, patented his process, and in the same See also:year Parker and See also:Robinson, working independently, patented a similar one. The two inventors then co-operated, an experimental plant was run successfully, and the See also:patents were taken over by the leading manufacturers. With the See also:object of obtaining a valuable by-product in See also:place of the slag produced in this furnace, several patentees (e.g. Hilbert and See also:Frank, Billaudot, See also:Bradley and See also:Jacobs, and others) have sought to combine the manufacture of calcium See also:carbide and phosphorus by using only calcium phosphate and carbon, effecting See also:direct reduction by carbon at a high temperature. The crude phosphorus is purified by melting under water and then filtering through animal See also:black and afterwards through See also:chamois See also:leather, or by treating it, when molten, with chromic acid ,or a mixture of See also:potassium bichromate and sulphuric acid; this causes the impurities to rise to the See also:surface as a scum which can be skimmed off. It is usually sent on the See also:market in the form of sticks, which were at one See also:time prepared by sucking the molten material up See also:glass tubes; but the dangers to the workmen and other disadvantages of this method have led to its replacement by a continuous process, in which the phosphorus leaves the melting-pot for a See also:pipe surrounded by water, in which it solidifies and can be removed as a continuous See also:rod. Properties.—When perfectly pure phosphorus is a white, trans-See also:parent, waxy solid, but as usually prepared it is yellowish owing to the presence of the allotropic " red phosphorus," J. Boeseken (Abs. Jour. Chem. Soc., 1907, H. 343, 760) prepares perfectly pure phosphorus by See also:heating the crude product with chromic acid See also:solution, washing and drying in a vacuum, first at 400, then at 8o°. It remains colourless in vacuum tubes in the dark, but on exposure it rapidly turns yellow. At 25° to 300 C. it is soft and flexible, but it hardens when strongly cooled, and can then only be cut with. difficulty. The fracture is distinctly crystalline; large Crystals, either See also:regular dodecahedra or octahedra, may be obtained by See also:crystallization from carbon bisulphide, See also:sulphur chloride, &c., or by sublimation. It is a non-conductor of See also:electricity. Its See also:density at o° is 1.836; this regularly diminishes up to the melting-point, 44.3°, when a sudden drop occurs. Molten phosphorus is a viscid, oily, highly refractive liquid, which may be supercooled to 32° before solidification. It boils at 290°, forming a colourless vapour which just about the boiling-point corresponds in density to tetratomic molecules, P4; at 1500° to 1700°, however, Biltz and See also:Meyer detected See also:dissociation into P2 molecules. See also:Beckmann obtained P4 molecules from the boiling-point of carbon bisulphide solutions, and See also:Hertz arrived at the same conclusion from the lowering of the freezing-point in See also:benzene solution; E. See also:Paterno and Nasini, however, detected dissociation. Phosphorus is nearly insoluble in water, but dissolves in carbon bisulphide, sulphur chloride, benzene and oil of See also:turpentine. The element is highly inflammable, taking See also:fire in See also:air at 34 and burning with a See also:bright white See also:flame and forming dense white clouds of the pentoxide; in perfectly dry air or See also:oxygen, however, it may be distilled unchanged, H. B. See also:Baker showing that a trace of water vapour was necessary for combination to occur. When exposed to the air a stick of phosphorus undergoes slow See also:combustion, which is revealed by a greenish-white phosphorescence when the stick is viewed in the dark. This phenomenon wasminutely studied by Boyle, who found that solutions in some essential See also:oils .(oil of See also:cloves) showed the same See also:character, whilst in others (oils of See also:mace and aniseed) there was no phosphorescence. He also noticed a strong See also:garlic-like odour, which we now know to be due to See also:ozone. See also:Frederick Slare noticed that the luminosity increased when the air was rarefied, an observation confirmed by Hawksbee and Homberg, and which was possibly the basis of See also:Berzelius's theory that the luminosity depended on the volatility of the element and not on the presence of oxygen. Lampadius, however, showed that there was no phosphorescence in a Torricellian vacuum; and other experimenters proved that oxygen was essential to the process. It depends on the partial pressure of the oxygen and also on temperature. In compressed air at See also:ordinary temperature there is no glowing, but it may be brought about by heating. Again, in oxygen under ordinary conditions there is no, phosphorescence, but if the See also:gas be heated to 25° glowing occurs, as is also the See also:case if the pressure be diminished or the gas diluted. It is also remarkable that many gases and vapours, e.g. Cl, Br, I,NH3, N20, NO2, H2S, S02, CS2, See also:CH4, C2H4, inhibit the phosphorescence. The theory of this action is not settled. It is certain that the formation of hydrogen peroxide and ozone accompany the glowing, and in 1848 See also:Schonbein tried to demonstrate that it depended on the ozone. E. Jungfleisch (Comptes rendus, 1905, 140, p. 444) suggested that it is due to the combustion of an See also:oxide more volatile than phosphorus, a view which appears to be supported by the observations of Scharff (Zeit. physik. Chem., 1908, 62, p. 178) and of L. and E. See also:Bloch (Comptes rendus, 1908, 147, p. 842). The element combines directly with the See also:halogens, sulphur and See also:selenium, and most of the metals See also:burn in its vapour forming phosphides. When finely divided it decomposes water giving hydrogen phosphide; it also reduces sulphurous and sulphuric acids, and when boiled with water gives phosphine and hypo-phosphorous acid; when slowly oxidized under water it yields hypophosphoric acid. Allotropic Phosphorus.—Several allotropic forms of phosphorus have been described, and in See also:recent years much See also:work has been done towards settling their identities. When the ordinary form immersed in water is exposed to light, it gradually loses its transparency and becomes coated with a thin film. This substance was regarded as an allotrope, but since it is not produced in non-aerated water it is probably an oxide. More important is the so-called " red phosphorus," which is produced by heating yellow phosphorus to about 230° for 24 See also:hours in an inert See also:atmosphere, or in closed vessels to 300°, .when the See also:change is effected in a few minutes. E. See also:Kopp in 1844 and B. C. See also:Brodie in 1853 showed that a trace of See also:iodine also expedited the change. The same form is also produced by submitting ordinary phosphorus to the silent electric See also:discharge, to sunlight or the ultra-See also:violet light. Since this form does not inflame until heated to above 350°, it is manufactured in large quantities for See also:consumption in the match See also:industry. The process consists in heating yellow phosphorus in iron pots provided with air-tight lids, which, however, bear a See also:long pipe open to the air. A small quantity of the phosphorus combines with the oxygen in the See also:vessel, and after this the operation is practically conducted in an atmosphere of See also:nitrogen with the additional safety from any See also:risk of See also:explosion. The product is ground under water, and any unchanged yellow form is eliminated by boiling with See also:caustic soda, the product being then washed and dried and finally packed in See also:tin boxes. The red -variety is remarkably different from the yellow. It is a dark red microcrystalline See also:powder, insoluble in carbon bisulphide, oil of turpentine, &c., and having a density of 2.2. It is See also:stable to air and light, and does not combine with oxygen until heated to above 3500 in air or 26o in oxygen, forming the pentoxide. It is also non-poisonous. When heated in a vacuum to 530° it sublimes, and on condensation forms microscopic needles. Hittorf's phosphorus is another crystalline allotrope formed by heating phosphorus with See also:lead in a sealed See also:tube to redness, and removing the lead by boiling the product with nitric and hydrochloric acid. It is also obtained by heating red phosphorus under pressure to 58o°. It forms a lustrous, nearly black crystalline See also:mass, composed of See also:minute rhombohedra. G. E. Linck and P. Moller (Ber., 1908, 41, p. 1404) have affirmed that the product of the first process always contains lead. E. See also:Cohen and J. Olie, Jun. (Abs. Jour. Chem. Soc., 19o9, ii. 998) regard red phosphorus as a solid solution of the white in Hittorf's, but this is contradicted by A. Stock (Ber., 1909, 42, p. 4510), who points out that ordinary red phosphorus melts at 6o5°-61o°, whilst Hittorf's melts at 620°; moreover, the latter is less reactive than the former at high temperatures. Another form was obtained by R. Schenck (Zeit. Elektrochem, 1905, ii. 117) as a See also:scarlet amorphous powder by deposition of solutions of phosphorus in the tri-iodide, tribromide or sulphide (P4S3). It phosphoresces in ozone, but not in air, and is non-poisonous; from its solution in alcoholic potash acids precipitate the hydride P12H6, and when heated it is transformed into the red modification. It has been used in combination with potassium chlorate as a See also:composition for matches to strike on any surface. Finally a black phosphorus was described by See also:Thenard as formed by rapidly-cooling melted phosphorus. Phosphine (phosphoretted hydrogen), PH3, a gas formed in the putrefaction of organic See also:matter containing phosphorus, was obtained by Gengembre (See also:Crell's See also:Ann., 1789, i. 450) by the action of potash upon phosphorus, the gas so prepared being spontaneously inflammable. Some time later See also:Davy, by heating phosphorous acid, obtained a phosphoretted hydrogen which was not spontaneously inflammable. These gases were considered to be distinct until Le Verrier (Ann, chim. phys., 1835 [21, 6o. p. 174) showed that the inflammability of Gengembre's phosphine was due to small quantities of liquid phosphoretted hydrogen, P2H4. Phosphine may be prepared by the decomposition of calcium phosphide with water (P2H4 being formed simultaneously) ; by the decomposition of phosphorous and hypo-phosphorous acids when strongly heated; and by the action of solutions of the caustic alkalis on phosphorus: P4+3NaOH+3H20= PH3+3NaH2PO2; hydrogen and P2H4 are produced at the same time, and the gas may be freed from the latter substance by passing into a hydrochloric acid solution of cuprous chloride, and heating the solution, when pure phosphine is liberated (Riban, Comptes rendus, 58, p. 581). The pure gas may also be obtained by heating phosphonium iodide with caustic potash (A. W. See also:Hofmann, Ber., 1871, 4, p. 200); by the decomposition of crystalline calcium phosphide or of See also:aluminium phosphide with water (H. See also:Moissan, See also:Bull. soc. chim., 1899 (3), 21, p. 926; Matignon, Comptes rendus, 1900, 130, p 1391) ; and by the reduction of phosphorous acid with nascent hydrogen. It is a colourless, extremely poisonous gas, possessing a characteristic offensive See also:smell, resembling that of rotting See also:fish. It becomes liquid at -9o° C., and solid at -133° C. (K. Olszewski, Monats., 1866, 7, p. 371). It is only slightly soluble in water, but is readily soluble in solutions of See also:copper sulphate, hypochlorous acid, and acid solutions of cuprous chloride. It See also:burns with a brightly luminous flame, and is spontaneously inflammable at about See also:loo° C. When mixed with oxygen it combines explosively if the mixture be under diminished pressure, and is violently decomposed by the halogens. It is also decomposed when heated with sulphur or with most metals, in the latter case with the liberation of hydrogen and formation of phosphide of the See also:metal. It combines with the halide derivatives of See also:boron and See also:silicon to form, e.g. PH3.2BF3, 2PHa-SiCl4 (Besson, Comptes rendus, 189o, no, 8o, pp. 240, 516; 1891, 113, p. 78), with the halogen acids to form phosphonium salts, PH4X (X=CI,Br,I), and with sodammonium and potassammonium to form PH2Na, PH2K (Joannis, Comptes rendus, 1894, 119, p. 557). It oxidizes slowly in air, and is a reducing See also:agent. It decomposes when heated, hydrogen and red phosphorus being formed. Liquid Phosphoretted Hydrogen, P2H4, first obtained by P. Thenard (Comptes rendus, 1844, 18, p. 652) by decomposing calcium phosphide with warm water, the products of reaction being then passed through a U tube surrounded by a freezing mixture (see also L. Gattermann, Ber., 189o, 23, p. 1174). It is a colourless liquid which boils at 57°-58 C. It is insoluble in water, but soluble in See also:alcohol and See also:ether. It is very unstable, being readily decomposed by heat or light. By passing the products of the decomposition of calcium phosphide with water over granular calcium chloride, the P2H4 gives a new hydride, P12H6 and phosphine, the former being an odourless, See also:canary-yellow, amorphous powder. When heated in a vacuum it evolves phosphine, and leaves an See also:orange-red residue of a second new hydride, P9H2 (A. Stock, W. Bottcher, and W. Lenger, Ber., 1909, 42, pp. 2839, 2847, 2853). Solid Phosphoretted Hydrogen, P4H2, first obtained by Le Verrier (loc. cit.), is formed by the action of phosphorus trichloride on gaseous phosphine (Besson, Comptes rendus, III, p. 972); by the action of water on phosphorus di-iodide and by the decomposition of calcium phosphide with hot concentrated hydrochloric acid. It is a yellowsolid, which is insoluble in water. It burns when heated to about 200° C. Oxidizing agents decompose it with See also:great violence. When warmed with alcoholic potash it yields gaseous phosphine, hydrogen and a hypophosphite. It reduces See also:silver salts. Phosphonium Salts.—The chloride, PH4CI, was obtained as a crystalline solid by Ogier (Comptes rendus, 1879, 89, p. 705) by combining phosphine and hydrochloric acid gas under a pressure of from 14-20 atmospheres; it can also be obtained at --30° to -35° C. under ordinary atmospheric pressure. It crystallizes in large trans-parent cubes, but rapidly dissociates into its constituents on exposure. The bromide, PH4Br, was first obtained by H. See also:Rose (Fogg. Ann., 1832, 24, p. 151) from phosphine and hydrobromic acid; it also results when phosphorus is heated with hydrobromic acid to too-120° C. in sealed tubes (Damoiseau, Bull. soc. chim., 1881, 35, p. 49). It crystallizes in colourless cubes, is deliquescent, and often inflames spontaneously on exposure to air. It is readily decomposed by water and also by carbonyl chloride (Besson, Cornptes rendus, 1896, 122, p. 140): 6PH4Br + 500012 = toHCl + 5CO =1- 6HBr + 2PH3 + P4H2. The iodide, PH4I, first prepared by J. See also:Gay-Lussac (Ann. chim. phys., 1814, 91, p. 14), is usually obtained by the action of water on a mixture of phosphorus and iodine (A. W. Hofmann, Ber., 1873, 6, p. 286). It is also prepared by the action of iodine on gaseous phosphine, or by heating amorphous phosphorus with concentrated hydriodic acid solution to 16o° C. It crystallizes in large cubes and sublimes readily. It is a strong reducing agent. Water and the caustic alkalis readily decompose it with liberation of phosphine and the formation of iodides or hydriodic acid. It is also decomposed by carbonyl chloride (Besson, loc. cit.). 4PHSI -}-800012 =16HC1+8C0+P214+2 P. Just as the See also:amines are derived from See also:ammonia, so from phosphine are derived the See also:primary, secondary and See also:tertiary organic phosphines by the See also:exchange of hydrogen for alkyl See also:groups, and corresponding to the phosphonium salts there exists a See also:series of organic phosphonium bases. The primary and secondary phosphines are produced when the alkyl iodides are heated with phosphonium iodide and See also:zinc oxide to 15o C. (A. W. Hofmann, Ber., 1871, 4, pp. 430, 6o5), thus: 2 RI + 2 PH4I + ZnO = 2 R•PH2•HI + ZnI2 + See also:H2O, 2RI + PH4I + ZnO = R3.PH•HI + ZnI2 + H2O. The reaction mixture on treatment with water yields the primary phosphine, the secondary phosphine being then liberated from its hydriodide by caustic soda. The tertiary phosphines, discovered by L. Thenard (Comptes rendus, 1845, 21, p. 144; 1847, 25, p. 892), are formed (together with the See also:quaternary phosphonium salts) by heating alkyl iodides with phosphonium iodide to 150-18o° C.: PH4I+3CH3I = P(See also:CH3)3HI +3HI; P(CH3)3HI + CH3I = P(CH3)4I + HI (see also Fireman, Ber., 1897, 30, p. Io88). They are also formed by the interaction of phosphorus trichloride and zinc alkyls (Cahours and Hofmann, Ann., 1857, 104, p. I): 2PC13+3 Zn (See also:C2H6)2=3ZnC12+ 2 P (C2H6) 3. The primary and secondary phosphines are colourless compounds, and with the exception of methyl phosphine are liquid at ordinary temperature. They possess an unpleasant odour, fume on exposure to air, show a neutral reaction, but combine with acids to form salts. They oxidize very rapidly on exposure, in many cases being spontaneously inflammable. On oxidation with nitric acid the primary compounds give monoalkyl phosphinic acids, R.PO(OH)2, the secondary yielding dialkyl phosphinic acids, R2PO(OH). The primary phosphines are very weak bases, their salts with acids being readily decomposed by water. The tertiary phosphines are characterized by their readiness to pass into derivatives containing pentavalent phosphorus, and consequently they form addition compounds with sulphur, carbon bisulphide, See also:chlorine, See also:bromine, the halogen acids and the alkyl halides with great readiness. On oxidation they yield phosphine oxides, R3P•O. The quaternary phosphonium salts resemble the corresponding nitrogen compounds. They are stable towards aqueous alkalis, but on digestion with moist silver oxide yield the phosphonium hydroxides, which are stronger bases than the caustic alkalis. They differ from the organic ammonium hydroxides in their behaviour when heated, yielding phosphine oxides and See also:paraffin See also:hydrocarbons: R4P•OH=R3PO+RH. The boiling-points of some members of the series are shown in the table Primary. Secondary. Tertiary. Methyl . . — 14° C. 25° C. 40-42° C. See also:Ethyl + 25° C. 85° C. 128° C. Isopropyl . . . 41° C. 118° C. — Isobutyl 62° C. 153° C. 215° C. Isoamyl 107° C. 210-215° C. 3oo° C.(?) The alkyl phosphinic acids are colourless crystalline compounds which are easily soluble in water and alcohol. They yield two series of salts, viz. RHM.PO3 and RM2PO3 (M =metal). The dialkyl phosphinic acids are also colourless compounds, the See also:majority of which are insoluble in water. They yield only one series of salts. Oxides.—Phosphorus forms three well-defined oxides, P4O6, P2O4 and P203 two others, P4O and, P20, have been described. Phosphorus suboxide, P40, is said to be formed, mixed with the other oxides, when the element is burnt in a limited See also:supply of air or in pure oxygen under reduced pressure (E. Jungfleisch, Abs. Jour. Chem. Soc., 1907, ii. 761), and also when a solution of phosphorus in the trichloride or tribromide is exposed to light. It is a yellow or red powder which becomes dark red on heating; it is stable in air; and can be heated to 300° without decomposition. Its existence, however, has been denied by A. Stock (Abs. Jour. Chem. Soc., 1910, ii. 121). The oxide P2O was obtained by Besson (Comptes rendus, 1897, 124, p. 76j; 1901, pp. 132, 1556) by heating a mixture of phosphonium bromide and phosphorus oxychloride in sealed tubes to 50°. Phosphorus oxide, P4O6, discovered by See also:Sage in 1777, is a product of the limited combustion of phosphorus in air. It may be conveniently prepared by passing a rapid current of air over burning phosphorus contained in a combustion tube, and condensing the product in a metal condenser, from which it may be removed by heating the condenser to 5o°—60° (See also:Thorpe and Tutton, Jour. Chem. Soc., 1890, pp. 545, 632; 1891, p. 1019). Jungfleisch has obtained it by carrying out the combustion with oxygen under reduced pressure, or diluted with an inert gas. It forms crystals, apparently See also:monoclinic, which melt at 22.5 to a clear, colourless, See also:mobile liquid of boiling-point 173-1°. Its specific gravity is 2.135 at 21 °. Vapour density and cryoscopic determinations point to the double See also:formula, P4O6. It is comparatively stable up to zoo, but when heated in a sealed tube to 440° it gives phosphorus and the tetroxide P2O4. It is unaffected by light when pure, but if phosphorus be See also:present, even in minute quantity, it turns yellow and ultimately dark red. It oxidizes on exposure to air to the pentoxide, and with a brilliant inflammation when thrown into oxygen at 5o°-6o°. It slowly reacts with See also:cold water to form phosphorous acid; but with hot water it is energetically decomposed, giving much red phosphorus or the suboxide being formed with an explosive See also:evolution of spontaneously inflammable phosphoretted hydrogen; phosphoric acid is also formed. With dilute alkalis phosphites are slowly formed, but with concentrated solutions the decomposition follows the same course as with hot water. With chlorine it gives phosphoryl and " metaphosphoryl " chlorides, the action being accompanied with a greenish flame; bromine gives phosphorus pentabromide and pentoxide which interact to give phosphoryl and " metaphosphoryl " bromides; iodine gives phosphorus di-iodide, P2I4, and pentoxide, P105; whilst hydrochloric acid gives phosphorus trichloride and phosphorous acid, which interact to form free phosphorus, phosphoric acid and hydrochloric acid. It combines violently with sulphur at 16o° to form phosphorus rulphoxide, P4O6S4, which forms highly lustrous tetragonal plates (after sublimation), melting at 102 and boiling at 295°; it 1s decomposed by water into sulphuretted hydrogen and metaphosphoric acid, the latter changing on See also:standing into orthophosphoric acid. Sulphur trioxide and sulphuric acid oxidize phosphorus oxide, giving the pentoxide and sulphur dioxide, whilst sulphur chloride, S2C12, gives phosphoryl and thiophosphoryl chlorides, free sulphur and sulphur dioxide. Ammonia also reacts immediately, giving phosphorus diamide, P(OH)(See also:NH2)2, and the corresponding ammonium See also:salt. Phosphorous oxide is very poisonous, and is responsible for the See also:caries set up in the jaws of those employed in the phosphorus See also:industries (see below). It is probable, however, that pure phosphorous oxide vapour is odourless, and the odour of phosphorus as ordinarily perceived is that of a mixture of the oxide with ozone. Phosphorus tetroxide, P2O4, was obtained by Thorpe and Tutton by heating the product of the limited combustion of phosphorus in vacuo as a sublimate of transparent, highly lustrous, orthorhombic crystals. They are highly deliquescent, and form with water a mixture of phosphorous and phosphoric acids: P2O4+3H2O=H3POs-IH3PO4. The vapour density at about 1400° is 230, i.e. slightly less than that required by P5016 (See also:West, Jour. Chem. Soc., 1902, p. 923). Phosphoric oxide, or phosphorus pentoxide, P4O10, formed when phosphorus is burned in an excess of air or oxygen, or from dry phosphorus and oxygen at atmospheric pressure (Jungfleisch, loc. cit.), was examined by Boyle and named " See also:flowers of phosphorus " by See also:Marggraf in 1740. It is a soft, flocculent powder, which on sublimation forms transparent, monoclinic crystals. It is extremely deliquescent, hissing when thrown into water, with which it combines to form phosphoric acid. It is reduced when heated with carbon to phosphorus, carbon monoxide being formed simultaneously. Its vapour density at 1400° points to the double formula (West, Jour. Chem. Soc., 1896, p. 154). Oxyacids.—Phosphorus forms several oxyacids: hypophosphorous acid, H3PO2, and hypophosphoric acid, H4P2O6 or H2PO3, of which the anhydrides are unknown; phosphorous acid, H3PO3, derived from P4O6; monoperphosphoric acid, H3PO5; perphosphoric acid, H4P2O2; and See also:meta-, pyro-, and ortho-phosphoric acids, derived from P4Olo, for which see PHOSPHATES. Hypo phosphorous acid, HP(OH)2, discovered by See also:Dulong in 1816, and obtained crystalline by See also:Thomson in 1874 (Ber., 7, p. 994), is prepared in the form of its See also:barium salt by warming phosphorus with baryta water, removing the excess of baryta by carbon dioxide, and crystallizing the filtrate. The acid may be prepared by evaporating in a vacuum the solution obtained by decomposing the barium salt with the See also:equivalent amount of sulphuric acid. The acid forms a white crystalline mass, melting at 17.4° and having a strong acid See also:xx1. 16reaction. Exposure to air gives phosphorous and phosphoric acids, and on heating it gives phosphine and phosphoric acid. A characteristic reaction is the formation of a red precipitate of cuprous hydride, Cu2H2, when heated with copper sulphate solution to 6o°. It is a monobasic acid forming salts which are permanent in air, but which are gradually oxidized in aqueous solution. On heating they yield phosphine and leave a residue of pyrophosphate, or a mixture of meta- and pyrophosphates, with a little phosphorus. They react as reducing agents. On boiling with caustic potash they evolve hydrogen, yielding a phosphate. Phosphorous acid, P(OH)3, discovered by Davy in 1812, may be obtained by dissolving its anhydride, .P4Oe, in cold water; by immersing sticks of phosphorus in a solution of copper sulphate contained in a well-closed See also:flask, filtering from the copper sulphide and precipitating the sulphuric acid simultaneously formed by baryta water, and concentrating the solution in vacuo; or by passing chlorine into melted phosphorus covered with water, the first formed phosphorus trichloride being decomposed by the water into phosphorous and hydrochloric acids. It may also be prepared by leading a current of dry air into phosphorus trichloride at 6o and passing the vapours into water at o°, the crystals thus formed being drained, washed with See also:ice-cold water and dried in a vacuum. The crystals melt at 70°. The acid is very deliquescent, and oxidizes on exposure to air to phosphoric acid. It decomposes on heating into phosphine and phosphoric acid. It is an energetic reducing agent; for example, when boiled with copper sulphate metallic copper is precipitated and hydrogen evolved. Although nominally tribasic the commonest metallic salts are dibasic. Organic See also:ethers, however, are known in which one, two and three of the hydrogen atoms are substituted (See also:Michaelis and See also:Becker, Ber., 1897, 30, p. 1003). The metallic phosphites are stable both dry and in solution; when strongly heated they evolve hydrogen and yield a pyrophosphate, or, especially with the heavy metals, they give hydrogen and a mixture of phosphide and pyrophosphate. Hypophosphoric acid, H4P2O6 or H2PO3, discovered by Salzer in 1877 among the oxidation products of phosphorus by moist air, may be prepared by oxidizing phosphorus in an aqueous solution of copper nitrate, or by oxidizing sticks of phosphorus under water, neutralizing with See also:sodium carbonate, forming the lead salt and decomposing this with sulphuretted hydrogen (J. See also:Cavalier and E. Cornee, Abs. Jour. Chem. Soc., 1910, 11. 31). The aqueous solution may be boiled without decomposition, but on concentration it yields phosphorous and phosphoric acids. Deliquescent, rectangular tablets of H4P2O62I-I2O See also:separate out on concentrating a solution in a vacuum, which on drying further give the acid, which melts at 55°, and decomposes suddenly when heated to 70° into phosphorous and metaphosphoric acids with a certain amount of hydrogen phosphide. The solution is stable to oxidizing agents such as dilute hydrogen peroxide and chlorine, but is oxidized by potassium permanganate to phosphoric acid; it does not reduce salts of the heavy metals. With silver nitrate it gives a white precipitate, Ag4P2O5. The sodium salt, Na4P2O4.1oH2O, forms monoclinic prisms and in solution is strongly alkaline; the acid salt, Na3HP2O6.9H2O, forms monoclinic tablets. The formula of the acid is not quite definite. Cryoscopic measurements on the sodium salt points to the double formula, but the organic See also:esters appear to be derived from H2PO3 (see A. See also:Rosenheim and M. Pritze, Ber., 1908, 41, 2708; E. Cornee, Abs. Jour. Chem. Soc., 1910, ii. 121). Monoperphosphoric and perphosphoric acids, H3PO5 and H4P2O6, were obtained by J. Schmidlin and P. Massini (Ber., 1910, 43, 1162). The first is formed when 30 % hydrogen peroxide reacts with phosphorus pentoxide or meta- or pyrophosphoric acids at See also:low temperatures and the mixture diluted with ice-cold water. The solution is strongly oxidizing, even converting manganous salts to permanganates in the cold, a property not possessed by monopersulphuric acid. Perphosphoric acid is formed when pyrophosphoric acid is treated with a large excess of hydrogen peroxide. Halogen Compounds. Phosphorus trifluoride, PF3, discovered by Davy, may be obtained mixed with the pentafluoride; by direct combination of its elements; from the tribromide and See also:arsenic trifluoride (Maclvor) ; from the tribromide and zinc fluoride, and from dried copper phosphide and lead fluoride (H. Moissan). It is a colourless, non-fuming gas, which gives a colourless, mobile liquid at —to° and 20 atmospheres; the liquid boils at -95° and solidifies at -160° (Moissan, Comptes rendus, 1904, 138, p. 789). It does not burn in air, but explodes, under the action of a flame or the electric spark, when mixed with See also:half its See also:volume of oxygen, giving the oxyfluoride, POF5. It is slowly decomposed by water giving hydrofluoric and phosphorous acids, or, in addition, fluorphosphorous acid, HPF4. It has no action on glass in the cold, but when heated it gives phosphorus and silicon tetrafluoride. Phosphorus pentafluoride, PF5, discovered by Thorpe (Prot. See also:Roy. Soc., 1877, 25, p. 122), may be obtained by burning the trifluoride in See also:fluorine, from the pentachloride and arsenic trifluoride and from the trifluoride and bromine, the first formed fluorobromide, PF3Br2, decomposing into the pentabromide and pentafluoride: 5PF3Br2=3PF5-l--2PBr5. It is a colourless gas 41 times heavier than air, and liquefies at 15° under 40 atmospheres, solidifying when the pressure is diminished. It is incombustible and extinguishes flame. It fumes in moist air and is quickly decomposed by water giving hydrofluoric and phosphoric 11 acids. It does not dissociate on heating as do the pentachloride and pentabrornide, thus indicating the existence of pentavalent phosphorus in a gaseous See also:compound; dissociation, however, into the trifluoride and free fluorine may be brought about by See also:induction See also:sparks of 150 to 200 mm. in length. It combines directly with ammonia in the proportion 2PF5:5NH3, and with nitrogen peroxide at -to° in the proportion PFs:NO2. Phosphorus lrifluorodichloride, PF3Cl2, prepared from chlorine and the trifluoride, is a pungent-smelling gas, which at 250° gives the pentachloride and fluoride. The trifluorodibromide (see above) is an See also:amber-coloured mobile liquid. Phosphoryl trifluoride, POF3, may be obtained by exploding 2 volumes of phosphorus trifluoride with i volume of oxygen (Moissan, 1886) ; by heating 2 parts of finely-divided See also:cryolite and 3• parts of phosphorus pentoxide (Thorpe and Hambly, Jour. Chem. Soc., 1889, p. 759); or from phosphoryl chloride and zinc fluoride at 4o° to 5o°. It is a colourless fuming gas, which liquefies under ordinary pressure at -50°, and under a pressure of 15 atmospheres at 16°; it may be solidified to a See also:snow-like mass. Water gives hydrofluoric and phosphoric acids. The corresponding sulphur compound, thiophosphoryl fluoride, PSF3, obtained by heating lead fluoride and phosphorus pentasulphide to 200°, is a colourless gas, which may be condensed to a clear transparent liquid. It spontaneously inflames in air or oxygen; and when the gas is issuing from a See also:jet into air the flame is greyish See also:green; with a faintly luminous and yellow tip; the flame is probably one of the coldest known. The combustion probably follows the See also:equation PSF3-{-02=PF3+S02, the trifluoride at a higher temperature decomposing according to the equations: IoPF3+502=6PFs+2P20s, 2PF3+02=2POF3, the See also:complete re-action tending to the equation: IoPSF3+1502=6PF5+2P205+ 1oSO2. The gas dissolves in water on shaking; PSF3+4H20= H3S+H3PO4+3HF, but is more readily taken up by alkaline solutions with the formation of fluoride and thiophosphate: PSF3+ 6NaOH = Na3PSO3+3NaF. Heated in a glass tube it gives silicon fluoride, phosphorus and sulphur, PSF3=PF3+S; 4PF3+3SiO2= 3SiF4+P4+302. Electric sparks give at first free sulphur and the trifluoride, the latter at a higher temperature splitting into the pentafluoride and phosphorus. With dry ammonia it gives ammonium fluoride and a compound P(NH2)2SF. Phosphorus trichloride or phosphorous chloride, PCIs, discovered by Gay-Lussac and Thenard in 18o8, is obtained by passing a slow current of chlorine over heated red phosphorus or through a solution of ordinary phosphorus in carbon disulphide (purifying in the latter case by fractional See also:distillation). It is a colourless, mobile liquid of specific gravity 1.6128 at o° and boiling-point 76°. With chlorine it gives the pentachloride, PCIs, and with oxygen when heated phosphoryl chloride, POCI3. Water gives hydrochloric and phosphorous acids, with separation of red phosphorus if the water be hot. When led with hydrogen into liquid ammonia it gives NH : PNH2, which on See also:elevation of temperature &ives P2(NH)3 (Joannis, See also:Corn pies rendus, 1904, 139, p. 364). By submitting a mixture of phosphorous chloride and hydrogen to an electric discharge A. Besson and A. See also:Fournier (See also:Cosa pies rendus, 1901, 150, p. 102) obtained phosphorus dichloride, P2CI4, as a colourless, oily, strongly fuming liquid, freezing at -28° and boiling at 180° with decomposition. With water it gave phosphorous acid and a yellow indefinite solid. It decomposes slowly at ordinary temperatures. Phosphorus pentachloride, PCIs, discovered by Davy in 1810 and analysed by Dulong in 1816, is formed from chlorine and the trichloride. It is a See also:straw-coloured solid, which by See also:fusion under pressure gives prismatic crystals. It sublimes when heated, but under pressure it melts at 148°, giving a normal vapour density, but on further heating it dissociates into the trichloride and chlorine; this dissociation may be retarded by vapourizing in an atmosphere of chlorine. It fumes strongly in moist air, giving hydrochloric acid and phosphoryl chloride, POCI3; with water it gives phosphoric and hydrochloric acids. Phosphoryl trichloride or phosphorus oxychloride, POC13, corresponding to phosphoric acid, (HO)3PO, discovered in 1847 by See also:Wurtz, may be produced by the action of many substances containing hydroxy groups on the pentachloride; from the trichloride and potassium chlorate; by leaving phosphorus pentoxide in contact with hydrochloric acid: 2P206+3HC1=POC13+3HP03; or by heating the pentachloride and pentoxide under pressure: 3PCIs+ P3Os=5POCl3. It is a colourless liquid, boiling at 107.2°, and when solidified it melts at o•8°. Water gives hydrochloric and phosphoric acids; dilute alcohol gives monoethyl phosphoric acid, C2H5•H2PO4, whilst See also:absolute alcohol gives triethyl phosphate, (C2H5)3PO4. Pyrophosphoryl chloride, P3O3C14, corresponding to pyrophosphoric acid, was obtained by Geuther and Michaelis (Ber., 1871, 4, p. 766) in the oxidation of phosphorus trichloride with nitrogen peroxide at low temperature; it is a colourless fuming liquid which boils at about 212° with some decomposition. With water it gives phosphoric and hydrochloric acids. Thiophosphoryl chloride, PSCI3, may be obtained by the direct combination of sulphur with the trichloride; from sulphuretted hydrogen and the pentachloride; from See also:antimony trisulphide and the pentachloride; by heating the pentasulphide with the pentachloride; and by dissolving phosphorus in sulphur chloride and distilling the solution: 2P+3S,Cl2= 4S+2PSCIs. It is a colourless mobile liquid, boiling at 1251 ° and having a pungent, slightly aromatic odour. It is slowly decomposed by water giving phosphoric and hydrochloric acids, withsulphuretted hydrogen; alkalis form a thiophosphate, e.g. PS(OK)3, and a chloride. Phosphorus tribromide, PBr3, prepared by mixing solutions of its elements in carbon disulphide and distilling, is a transparent, mobile liquid, boiling at 173° and resembling the trichloride chemically. The pentabromide, PBrs, which results from phosphorus and an excess of bromine, is a yellow solid, and closely resembles the pentachloride. The bromochloride, PCI3Br2, is an orange-coloured solid formed from bromine and the trichloride, into which components it decomposes at 35°. Phosphoryl tribromide, POBr3, is a solid, melting at 45° and boiling at 195°. Thiophosphoryl bromide, PSBr3, obtained after the manner of the corresponding chloride, forms yellow octahedra which melt at 38°, and have a penetrating, aromatic odour. With water it gives sulphur, sulphuretted hydrogen, hydrobromic, phosphorous and phosphoric acids, the sulphur and phosphorous acid being produced by the interaction of the previously formed sulphuretted hydrogen and phosphoric acid. Pyrophosphoryl thiobromide, (PBr2S)2S, and metaphosphoryl thiobromide, PSsBr, are also known. Phosphorus forms three iodides. The subiodide, P4I, was obtained by R. Bculough (Comptes rendus, 1905, 141, p. 256), who acted with dry iodine on phosphorus dissolved in carbon disulphide; with alkalis it gives P4(OH). The di-iodide and tri-iodide are formed similarly; the first is deposited as orange-coloured prisms which melt at 11o° to a red liquid (see Doughty, Jour. Amer. Chem. Soc., 1905, 27, p. 1444), whilst the second forms dark-red hexagonal plates which melt at 55°. Sulphides and Thio-acids.—Phosphorus and sulphur combine energetically with considerable rise of temperature to form sulphides. The researches of A. Stock (Ber., 1908, 41, pp. 558, 657; 1909, 42, p. 2062; 1910, 43, pp. 150, 414) show that three exist, P4S3, P4S7, P2S5. The first is prepared by heating red phosphorus with finely powdered sulphur in a tube sealed at one end and filled with carbon dioxide. The product is extracted with carbon disulphide and the residue distilled in carbon dioxide. It forms light yellow crystals from benzene, which melt at 1725° and See also:boil at 4070-408° with slight decomposition. Alkalis give hydrogen and phosphine. The second, P4S7, is obtained by heating a mixture of red phosphorus and sulphur in the proportions given by P4S7+5 % P4S3, and crystallizing from carbon disulphide in which P4S3 is readily soluble. It forms small, slightly yellow prisms, which melt at 310° and boil at 523°. The third, or pentasulphide, P2S6, was obtained as a substance resembling flowers of sulphur by A. Stock and K. Thiel (Ber., 1905, 38, p. 2719; 1910, 43, p. 1223), who heated sulphur with phosphorus in carbon disulphide solution with a trace of iodine to 120°-130°. It exists in two forms, one having the formula P4S10, and the other a See also:lower molecular See also:weight. With liquid ammonia it gives P2Ss•7NH3, which is a mixture of ammonium iminotrithiophosphate, P(SNH4)s: NH; and ammonium nitrilodithiophosphate, P(SNH4)2iN. Water converts the former into ammonium thiophosphate, PO(SNH4)3.H20, whilst the latter heated to 300° in a vacuum gives thiophosphoric nitrile, Ni.P:S (Stock, ibid., 1906, 39, p. 1967). Thiophosphates result on dissolving the pentasulphide in alkalis. Sodium monothiophosphate, Na3PS03•I2H20, is obtained by adding one P2Ss to six NaOH, adding alcohol, dissolving the precipitate in water and heating to 90°. On cooling the salt separates as white six-sided tablets. Sodium dithiophosphate, NasPS2O2.11 H2O, is obtained by heating the above solution only to 50°-55°, cooling and adding alcohol, which precipitates the dithio salt. On heating it gives the monothio salt. Sodium trithiophosphate appears to be formed when the pentasulphide acts with sodium hydrosulphide at 20°. All thiophosphates are decomposed by acids giving sulphuretted hydrogen and sometimes free sulphur. They also See also:act in many cases as reducing agents. Nitrogen Compounds.—Phosphorus pentachloride combines directly with ammonia, and the compound when heated to redness loses ammonium chloride and hydrochloric acid and gives phospham, PN2H4, a substance first described by Davy in 1811. It is a white, infusible, very stable solid, which decomposes water on heating, giving ammonia and metaphosphoric acid, whilst alkalis give an analogous reaction. With methyl and ethyl See also:alcohols it forms secondary amines (Vidal, Couples rendus, 1891, 112, p. 950; 1892, 115, p. 123). The diamide, PN2H4, was obtained by Hugot (ibid., 1905, 141, p. 1235) by acting with ammonia gas on phosphorus tribromide, or tri-iodide at -70°; it is very unstable, and decomposes at -25°. Phosphorus combines with nitrogen and chlorine to form several. polymeric substances of the See also:general formula (PNCl2) x, where x may be 1 , 3, 4, 5, 6, 7, or I I ; they maybe obtained by heating the pentachloride with ammonium chloride in a sealed tube and separating the mixture by fractional distillation (H. N. See also:Stokes, Amer. Chem. Jour., 1898, 2o, p. 740; also see Besson and Rosset, Comptes rendus, 1906, 37, p. 143). The commonest form is P3N3Cls, a crystalline solid, insoluble in water, but soluble in alcohol and ether. Several phosphoamides have been described. The diamide, PO (NH2)(NH), results when the pentachloride is saturated with ammonia gas and the first formed chlorophosphamide, PCl3(NH2)2, is decomposed by water. The triamide, PO(NH2)3, results from ammonia and phosphorus oxychloride. Both these compounds on heating give phosphomonamide, PON, of which a polymer (PON)2 had been described by Oddo (Gazz. chim. Ital., 1899, 29 (ii.), p. 330). Stokes (Amer. Chem. Jour.,
See also:independent feeling of the Eastern See also: See also:Photius See also:felt himself the See also:champion of Eastern See also:Christianity against Latin pretensions; and when in 863 See also:Nicholas finally anathematized and deposed him, he replied by a See also:counter-See also:excommunication. Meanwhile, the situation was suddenly changed by the See also:murder of Photius's See also:patron, Bardas, by See also:order of the See also:emperor See also:Michael, who was himself assassinated by his colleague See also:Basil in the following year 1867). The fall of Photius immediately ensued; he was removed from his See also:office and banished about the end of See also:September 867, a few days after the See also:accession of Basil, and See also:Ignatius was reinstated on the 23rd of See also:November. About 876 Photius was suddenly recalled to See also:Constantinople and entrusted with the See also:education of Basil's See also:children. On the See also:death of Ignatius, probably in See also:October 878, Photius, after a decent show of reluctance, again filled the patriarchal See also:throne. He then proceeded to obtain the formal recognition of the See also:Christian See also:world. In November 879 a See also:synod was convened at Constantinople. The legates of See also:Pope See also: After the death of Basil (886), his son and successor See also:Leo, who had formerly been devoted to Photius, but in recent years displayed great hatred towards him, deprived him of his office and banished him to the monastery of Bordi in See also:Armenia. From this time Photius disappears from See also:history. No letters of this See also:period of his life are extant, which leads to the inference that his imprisonment was severe. The precise date of his death is not known, but it is said to have occurred on the 6th of See also:February 1893, 15, P. 198 ; 1894, 16, pp. 123, 154) has described PO(OH)2NH2 and PO(OH) (NH2)2, whilst the compound PO(OH)NH was obtained by Schiff (Ann., 1857, 103, p. 168) by acting with ammonia on the pentoxide. ,Numerous other nitrogen compounds have been obtained. The atomic weight of phosphorus was determined by Berzelius, See also:Pelouze, Jacquelin, See also:Dumas, Schrotter, Brodie and See also:van der Plaats. More recent are the investigations of G. Ter Gazarian (See also:Comet. rend., 1909, 148, p. 1397) on hydrogen phosphide, which gave the value 30.906, and of G. P. See also:Baxter and G. See also: The hypophosphites have been recommended in pulmonary affections, being said to act as free phosphorus without being irritant, and the glycero-phosphates are certainly useful to stimulate See also:metabolism. Dilute phosphoric acid is used as a gastric stimulant. It does not resemble phosphorus in its physiological action and cannot be used to replace it. See also:Toxicology.—Poisonous amounts of phosphorus are frequently taken or administered, criminally or accidentally, it being easily accessible to the public in the form of matches or of See also:vermin pastes. They may have been swallowed several hours before symptoms of acute poisoning show themselves, with See also:nausea and vomiting, and a burning in the See also:oesophagus, See also:stomach and See also:abdomen. The important thing is to prevent the absorption of the See also:poison, so See also:emetics and purgatives should be given at once. Sulphate of copper, in doses of 3 to 5 gr., freely diluted and repeated every few minutes forms the harmless, black phosphide of copper, which is rapidly eliminated by the kidneys. The stomach may be washed out with warm water and then with a 2% o solution of permanganate of potash, an enema of the same solution being given. The old See also:French oil of turpentine is the best antidote to use in phosphorus poisoning, delaying the toxic effects; but ordinary oils are not only useless but harmful. When some time has elapsed before treatment and the phosphorus has become absorbed, the organic degenerative changes cannot be easily controlled. For the chronic form of See also:industrial poisoning in the manufacture of See also:lucifer matches—a form of See also:necrosis, known in England as " phossy See also:jaw " and in See also:France as mal chimique," a localized inflammatory infection of the periosteum, ending with the death and exfoliation of part of the bone see MATCH. Additional information and CommentsThere are no comments yet for this article.
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