From the CRC handbook of Chemistry and Physics, CRC Press, Cleveland, 55th ed., 1974-75 "The Elements" by C.R. Hammond. page B-6
PHOSPHORUS (Gr. phosphoros, light-bearing; ancient name for the planet Venus when appearing before sunrise), P; at. wt. 30.9736; at. no. 15; m.p. (white) 44.1 C; b.p. (white) 280 C; sp.gr. (white) 1.82,(red) 2.20, (black) 2.25 to 2.69; valence 3 or 5. Discovered in 1669 by Brand, who prepared it from urine. Phosphorus exists in four or more allotropic forms: white (or yellow), red, and black (or violet). White phosphorus has two modifications: alpha and beta with a transition temperature at -3.8 C. Never found free in nature, it is widely distributed in combination with minerals. Phosphate rock, which contains the mineral apatite - an impure tri-calcium phosphate - is an important source of the element. Large deposits are found in the U.S.S.R., in Morocco, and in Florida, Tennessee, Utah, Idaho, and elsewhere. Phosphorus is an essential ingreadient of all cell protoplasm, nervous tissue, and bones. Ordinary phosphorus is a waxy white solid; when pure it is colorless and transparent. It is insoluble in water, but soluble in carbon disulfide. It takes fire spontaneously in air, burning to the pentoxide. It is very poisonous 50 mg constituting an approximate fatal dose. The maximum recommended allowable concentration in air is 0.1 mg/cubic meter. White phosphorus should be kept under water as it is dangerously reactive in air, and it should be handled with forceps, as contact with the skin may cause severe burns. When exposed to sunlight or when heated in its own vapor to 250 C, it is converted to the red variety, which does not phosphoresce in air as does the white variety. This form does not ignite spontaneously and it is not as dangerous as white phosphorus. It should, however, be handled with care as it does convert to the white form at some termperatures and it emits higly toxic fumes of the oxides of phosphorus w hwen heated. The red modification is fairly stable, sublimes with a vapor pressure of 1 atm. at 417 C, and is used in the manufacture of safety matches, pyrotechnics, pesticides, incendiary shells, smoke bombs, tracer bullets, etc. White phosphorus may be made by several methods. By one process, tri-calcium phosphate, the essential ingredient of phosphate rock, is heated in the presence of carbon and silica in an electric furnace or fuel-fired blast furnace. ELementary phosphorus is liberated as vapor and may be collected under water. If desired, the phosphorus vapor and carbon monoxide produced by the reaction can be oxidized at once in the presence of moisteure or water to produce phosphoric acid-an important compound in making super-phosphate fertilizers. In recent years, concentrated phosphoric acids, which may contain as much as 70 to 75% P2O5 content, have become of great importance to agriculture and farm production. World-wide demand for fertilizers has caused record phosphate production in recent years. Phosphatessss are used in the production of special glasses, such as those used for sodium lamps. bone-ash, calciumphosphate, is also used to produce fine chinaware and to produce mono-clacium phosphate used in baking powder. Phosphorus is also important in the production of steels, phosphor bronze, and many other products. Tri-sodium phosphate is important as a cleaning agent, as a water-softener, and for preventing boiler scale and corrosion of pipes and boiler tubes. Organic compounds of phosphorus are important.
