Manufacture.— For the manufacture of ordinary phosphorus any kind of phosphate of lime might be used, and in fact mineral phosphates are used occasionally, though as a rule the bones of domestic animals are employed as a raw material. Such bones (apart from a large percentage of water and a small admixture of fats and other subsidiary organic components) consist essentially of two things, namely, (1) osseine— a nitrogenous organic compound, insoluble in water, but convertible by long treatment with hot water into a solution of “glue ”—and (2) an infusible and incombustible part,—the two being united together (perhaps chemically) into a cellular tissue. The following analysis of the humerus of an ox gives an idea of the constitution of the second part and its ratio to the whole. [table]

The percentages, however, in bones generally are subject to great variation. When bones are heated to redness in the absence of air the organic part is destroyed, and there remains ultimately a cellular tissue of bone-phosphate impregnated, so to speak, with finely-divided charcoal. This black residue, known as “bone-black,” is used largely for the decoloration of sugar-syrup, and, after having been exhausted in this direction, forms a cheap material for the manufacture of bone-ash and consequently of phosphorus; but, as a rule, the phosphorus-manufacturer makes his bone-ash direct from bones, by burning them in a furnace (constructed and wrought pretty much like a limekiln) between alternate layers of coal.

The burned bones (which retain their original shape) are ground up into granules of about the size of lentils, and these are then placed in a wooden tank coated inside with lead, to be decomposed by means of about their own weight of chamber-acid, i.e., sulphuric acid containing about 60 per cent, of real H 2 SO 4 . To accelerate the action the bone-meal is mixed with boiling water previous to the addition of acid, and steam may be passed into the magma when its temperature threatens to fall too low. The acid readily decomposes the carbonate of the boneash, and then acts, more slowly, on the phosphate, the process being completed in about twenty-four hours; and the result, in regard to the latter, is that about two-thirds of the phosphate are decomposed into sulphate of lime (gypsum), which separates out as a precipitate, and phosphoric acid, which unites with the residual one-third of the phosphate and the water into a solution of superphosphate of lime—

PA ¾g + ≈A< 1 .

To eliminate the gypsum the mass is diluted with water, allowed to settle, and the solution drawn off with lead syphons, then the residue is washed by decantation, and ultimately filtered off through a bed of straw contained in a cask with a perforated bottom. The spent heat of the distillation-furnace is utilized to concentrate the united liquors to about 1 ’ 45 specific gravity, when a remnant of gypsum separates out, which must be removed. The clarified liquor is then mixed with about one-tenth of its weight of granulated charcoal, and the whole evaporated in an iron basin until the mass is sufficiently dry to be passed through a copper sieve and granulated. The granules are heated cautiously over a fire, to be dehydrated as far as possible without loss of phosphorus (as phosphuretted hydrogen); and the dry mass is then transferred to fireclay retorts—either pear-shaped with bent-down necks, or cylinders, about 18 inches long and 4 inches in diameter, with straight necks—arranged within a powerful furnace. The condensers are made of earthenware, and must be so arranged that loss of phosphorus by combustion is avoided as far as possible; its condensation takes care of itself. One construction is to give the condenser the form of a bell-jar resting in a saucer containing water; lateral orifices in the bell serve to couple every two bells into one, to unite each with its retort-neck, and to send the vapour (of phosphuretted hydrogen, carbonic oxide, and other poisonous gases) into a chimney, where they take fire spontaneously, and the products are carried away by the draught. While the condensers are being adjusted the fire is kindled and raised very slowly, but ultimately forced up to the highest temperature which the retorts can stand, and maintained at this pitch until the appearance of the flames of the escaping vapours proves the absence from them of phosphorus, free or combined. This takes from thirty-six to forty-eight hours. The reduction-process, though in reality very complex, is in its principal features easily understood. The acid-phosphate behaves as if it were a mere mixture of -∣ × P 2 O 5 + ⅜ × P 2 O 5 3CaO (bone-phosphate). The quasi-free acid (⅜P 2 O 5 ) is reduced by the charcoal with formation of carbonic oxide and phosphorus-vapour, one-third of the phosphorus remaining in its original form of bone-phosphate.

The distillation of phosphorus is rather a dangerous operation, because the connecting pipes at the condensers are apt to get blocked up with frozen phosphorus, and consequently must be cleared from lime by copper or iron wires being pushed through them (at a certain risk to the operator). Another difficulty is that, although a retort may be quite whole in the ordinary sense, it may, and as a rule does, admit of the perspiration of phosphorus-vapour. To render retorts as nearly as possible impermeable to the vapour they are being provided with two or three coats of some kind of cement, such as a mixture of slaked lime and borax, or a magma of clay, horse-dung, and water. In the collecting and further manipulation of the phosphorus the dangerous inflammability of the substance demands that all operations be conducted under water.

As soon as the retorts have cooled down sufficiently the condensers are detached and their tubuli bunged up to prevent access of air to the inside. The necks of the retorts are knocked off and thrown into water to save the phosphorus which has condensed within them and to unite it with that of the condensers. From the analysis of the ox-bone quoted we calculate that its ash contains 17‘6 per cent, of phosphorus, of which two-thirds (=11'7 per cent.) should be recoverable as free phosphorus; according to Fleck, the yield of phosphorus is 8 per cent., while Payen puts it down at 8 to 10 per cent. But this crude phosphorus is largely contaminated with blown-over bone-ash and charcoal and with “red” phosphorus. Its purification used to be effected everywhere by melting it under water of about G0° C., and pressing it through chamois leather by means of a force-pump. In certain French works porous fireclay serves as a filtering medium, while superheated steam supplies at the same time the necessary heat and pressure. By the addition of coarsely-powdered charcoal to the phosphorus the clogging-up of the pores of the fireclay septum is precluded. A more effectual method of purification is to re-distil the crude (or perhaps the previously filtered) phosphorus from out of cast-iron retorts, the necks of which dip half an inch deep into water contained in a bucket. A chemical method of purification is that of Böttcher, who fuses the crude phosphorus (100 parts) under water, with addition of 3’5 parts of oil of vitriol and 3 ‘5 parts of bichromate of potash. The phosphorus passes, -with a feeble gas-evolution, into an almost colourless liquid, with a loss of only 4 per cent, of its weight, as against the 10 to 15 per cent, unavoidably involved in the distillation process. To bring the purified phosphorus into the traditional form of sticks it is fused under water and sucked up into slightly conical glass tubes about two-fifths of an inch wide and a foot long; the tubes are closed below with the finger and immersed in cold water to cause the contents to freeze. The solid stick is then pushed out by means of a rod, and cut into pieces with a pair of scissors. For emission into commerce the sticks are put into cylindrical wide-necked glass bottles, or into tin canisters, full of water, which latter had better be mixed with a sufficiency of alcohol or glycerin to prevent freezing (and bursting) in winter time.

Seubert, about 1&44, invented an ingenious apparatus for the continuous casting of phosphorus-sticks, consisting of a funnel-shaped vessel of copper, terminating below in a long horizontal copper tube, the outer end of which lies within a tank full of cold water. The phosphorus is placed in the funnel, covered with water, and the whole up to the cold-water tank raised (by means of a water-bath and steam-pipes) to a suitable temperature, matters being arranged so that the phosphorus freezes just on arriving at the exit end of the tube. The workman then catches the protruding button of phosphorus and pulls out an endless stick, which is cut up into pieces of the desired length. This ingenious apparatus, however, has not been found to work satisfactorily, and has been given up again in favour of some form of the old method. The loss of one-third of the phosphorus contained in the bone-ash, which is unavoidably involved in the ordinary method of phosphorus-making, can be avoided, according to Wohler, by adding finely-powdered quartz to the mixture which goes into the retorts. The superphosphate is then completely decomposed with formation of a residue of silicate, instead of phosphate, of lime. An improvement by Fleck aims at the utilization of the organic part of the bones. He proposes to recover the fat from the bones by boiling them with water and then the gelatin by digesting them in hydrochloric acid of 1Ό5 specific gravity. The gelatin remains in a coherent form; the phosphate passes into solution as mono-calcic salt, which is recovered by evaporation in crystals and then reduced by distillation with charcoal. None of these (and other) proposals have been much heeded; the manufacture of phosphorus at present, in fact, is almost a monopoly, the bulk of what occurs in commerce being produced by two firms, viz., Albright and Wilson of Oldbury, near Birmingham, and Coignet and Son in Lyons. According to E. Kopp, the production in 1874 amounted to 1200 tons.

Recently purified phosphorus is a slightly yellowish or colourless solid of about the consistence of beeswax. At low temperatures it is brittle; specific gravity == 1 · 83 at 10’ C. It fuses at 44° ’ 3 C. into a strongly light-refracting liquid of l·743 (Kopp) specific gravity. Neither in the solid nor in the liquid state does it conduct electricity. When heated further (in an inert atmosphere such as hydrogen or carbonic-acid gas) it boils at 290° C., and assumes the form of a colourless vapour which at 1040* C. is 4 ’ 5 times as heavy as air or 65T times as heavy as hydrogen, whence it follows that its molecular weight is 2 × 65Ί = 130 - 2 = very nearly four times the atomic weight of phosphorus (31Ό). Phosphorus is insoluble in water, more or less sparingly soluble in alcohol, ether, fatty oils, and oil of turpentine, and very abundantly soluble in bisulphide of carbon. When exposed to the air, and especially to moist air, it suffers gradual oxidation into phosphorous and phosphoric acids with evolution of a feeble light. Phosphorus does not phosphoresce in the absence of oxygen. Singularly, it does not phosphoresce in pure oxygen either, unless the tension of the gas be reduced to some point considerably below one atmosphere (Graham). Phosphorus is a most dangerous poison; doses of as little as 0 ’ 1 gramme ( = 1 - 5 grains) are known to have been fatal to adults. The heads of a few lucifer matches may suffice to kill a child. Phosphorus is used chiefly for the manufacture of lucifer matches (see Matches, vol. xv. pp. 625, 626) and also in the manufacture of iodide of methyl and other organic preparations used as auxiliary agents in the tar-colour industry. Phosphorus-paste, made by working up a small proportion of phosphorus melted under water in a hot mortar with flour, is used as poison for vermin.

Reel Phosphorus. — A red infusible solid which is always produced when ordinary phosphorus is made to burn in an insufficient supply of air, and also by the long-continued action of sunlight on phosphorus-sticks kept under water, used to be taken for a lower oxide of the element, until A. v. Schrötter of Vienna showed, in 1845, that it is nothing but an allotropic modification of the elementary substance. A given mass of ordinary phosphorus can be converted almost completely into the red modification by keeping it at 240° to 250° C. in the absence of air for a sufficient time. The addition of a trace of iodine to phosphorus at 200° C. brings about the conversion suddenly with large evolution of heat (Brodie). Red phosphorus is now an article of chemical manufacture. The phosphorus is simply heated, and kept at the requisite temperature, within a large iron pot which communicates with the atmosphere by only a narrow pipe. At a very slight expense of the material the air within the apparatus is quickly deoxygenated and converted into (inert) nitrogen. The requisite steady temperature is maintained by means of a bath of molten solder. By the mere effect of the heat the phosphorus becomes more and more viscid and darker and darker in colour, and is at last completely converted into a dark-red opaque infusible solid. This, however, always includes a small proportion of the ordinary modification, which is most readily extracted by powdering the crude product and exhausting it with bisulphide of carbon, which does not affect the red kind. A less expensive method is to boil the powdered raw product with successive quantities of caustic-soda ley, when the ordinary phosphorus only is dissolved as hypophosphite with evolution of phosphuretted hydrogen. The residue is washed and dried and then sent out in bottles or canisters like any ordinary chemical preparation. It is not at all affected by even moist air, nor by aerated water, hence it is neither phosphorescent nor poisonous. When heated in air to about 260° C. it begins to pass into the ordinary modification and consequently burns, readily enough, into the same phosphoric acid P 2 O 5 as ordinary phosphorus does. But its combustion-heat amounts to only 5070 Centigradeunits per unit-weight of fuel as against the 5953 units produced in the combustion of ordinary phosphorus. The balance of 883 units is the equivalent of the surplus of energy contained in the yellow as compared with the red modification. This accounts for the relative chemical inertness of the latter. The specific gravity of red phosphorus is 2 - 089 to 2’106 at 17°C.; its electric conductive power is about Ό00,000,1 of that of silver wire (Matthiesen). It is used in making safety-matches.

Metallic Phosphorus.— This, discovered by Hittorf, is obtained by heating ordinary phosphorus with lead in sealed-up tubes to redness for forty hours. After removal of the lead by nitric acid metallic phosphorus remains, partly in the shape of dark resplendent plates, partly in the form of microscopic rhombohedra. It requires a temperature of 358° to be converted into ordinary phosphorus-vapour. The specific gravity is 2 ’ 34 at 15° C.

Detection of Phosphorus.— The detection of (ord.) phosphorus in medico-legal cases offers no difficulty as long as the phosphorus has not disappeared by oxidation. In the case of a mass of food or the contents of a stomach the first step is to spread out the mass on a plate and view it in the dark. A very small admixture of phosphorus becomes visible by its phosphorescence. Failing this, the mass is distilled with water· from out of a glass flask connected with a glass Liebig’s condenser in a dark room. The minutest trace of phosphorus suffices to impart phosphorescence to the vapours at some stage of the distillation. Should this second test fail we must search for phosphorous acid, which may be there as a product of the oxidation of phosphorus originally present as such. To test for phosphoric acid would be of no use, as salts of this acid are present in all animal ⅛nd vegetable juices and tissues. Phosphorous acid, if present, can be detected by treating the mass, in a properly constructed gas-evolution apparatus, with pure hydrochloric acid and zinc. The hydrogen gas evolved must be purified by passing it over pieces of solid caustic potash, and made to stream out of a narrow platinum nozzle. If the reagents are pure and phosphorous acid is absent the gas burns with a colourless flame, which remains so even when depressed by means of a porcelain plate; in the presence of phosphorous acid the gas contains phosphuretted hydrogen, which causes the flame of the gas to exhibit a green core, at least when depressed by means of a porcelain plate. The test is very delicate, but in interpreting a positive result it must be remembered that it applies likewise to hypophosphorous acid, and that certain salts of this acid are recognized medicinal agents.

Of all phosphorus compounds ortho - phosphates are the commonest, and they can be detected by the tests given below under “Phosphates.” All other phosphorus compounds, when fused with carbonate of alkali and nitre, or heated in sealed-up tubes with strong nitric acid to a sufficient temperature, are changed so that the phosphorus assumes the form of ortho - phosphoric acid, which is easily detected. Either of the two operations named (by the mere action of the alkali or of the acid qua acid) converts what may be present of meta - phosphoric or pyro - phosphoric into ortho-phosphoric acid.

Phosphor-Bronze.— This name has been given to a class of useful metallic substances produced by the chemical union of either pure copper or of copper alloys with phosphorus. Most commercial copper is contaminated with a small proportion of its own suboxide, which, in the case of an otherwise pure metal, detracts from its tenacity and plasticity; and all ordinary bronze is subject to a similar contamination, because, whatever kind of copper may have been used in making it, the tin is sure to suffer partial oxidation, and some of this oxide, as Montefiori-Levi and Künzel found, remains diffused throughout the casting, and diminishes its homogeneity and solidity. Experience shows that both in the case of copper and bronze the oxygen present as metallic oxide can be removed by introduction into the fused metal of a judiciously limited proportion of phosphorus, which takes out the oxygen (and itself) into the slag it⅛ phosphate, and thus produces a purely metallic and consequently superior metal. A small excess of phosphorus in either case effects further improvement. A phosphor-copper containing 0Ί to 0’5 per cent, of the non-metallic element has all the plasticity of the pure metal coupled with higher degrees of hardness and solidity. An alloy of from 0’5 to 2’0 per cent, gives good castings, because, unlike the pure metal, it does not form blisters on solidifying. In the case of...