Chemical elements
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Applications of Phosphorus

Pyrotechnic Uses of Phosphorus

The quantity of phosphorus consumed in the match industry exceeds by far that required for all other purposes. The total consumption exceeds 1000 tons per annum, the greater part of which is worked up for matches, hundreds of millions of which are made per annum in factories in all parts of the world. The phosphorus is now applied in the red or scarlet form or as one of the sulphides (q.v.). The materials used in friction matches have varied greatly at different periods.

The first chemical matches are attributed to Chancel of Paris (1805) and were manufactured from 1812. They contained no phosphorus, but consisted of sticks of wood tipped with melted sulphur and then coated with a mixture of sugar and chlorate of potash. They were ignited by dipping in a bottle containing asbestos moistened with concentrated sulphuric acid. Similar applications of phosphorus have been described. Phosphoric tapers were made of wax coated with phosphorus, and were enclosed in sealed glass tubes. These were warmed and then opened, when the phosphorus burst into flame.

Friction matches, invented in England in 1827, were tipped with a mixture of antimony trisulphide, potassium chlorate and gum, and ignited by rubbing on sand-paper. The recognition of the superior properties of phosphorus as an ingredient of these miniature explosives dates from about 1833, when wooden matches, the heads of which contained phosphorus, appeared simultaneously in several countries. Attempts to prepare matches from yellow phosphorus had been made from about 1816 by Derosne and others, but it was only later discovered that the heads must be coated first with another combustible material such as sulphur to transmit the flame of the phosphorus-chlorate mixture. The first matches were both explosive and dangerous. Chlorate was later replaced by lead peroxide, then by red lead and manganese dioxide in 1837. The first safety matches, prepared by Bottger in 1848, were tipped with gum, sulphur and chlorates or chromates, and a similar process was patented by May in 1865. From about 1855 great quantities of safety matches were made in Sweden. These were struck by rubbing on a surface containing red phosphorus worked up with gum and antimony sulphide. The red phosphorus is often replaced by scarlet phosphorus or the sulphide. The ingredients are worked up with glue and powdered glass or emery and mechanically painted on the sides of the boxes. The match sticks are well soaked in paraffin wax or sulphur, and the ends then dipped in a warm mixture of chlorate, dichromate, red lead and antimony sulphide.

Recipes for matches have been the subject of numerous patents. The following is an example of the complexity of the mixtures:—

Potassium chlorate 450 parts, potassium dichromate 110 parts, glass powder 75 parts, sulphur 60 parts, iron oxide 25 parts, red phosphorus 7-8 parts, tragacanth 30 parts, gum arabic 110 parts.

The heads of lucifer matches, which will ignite on any rough surface, contain phosphorus in addition to the ingredients of the heads of safety matches. Accounts of the history and manufacture of matches may be obtained from the following sources:—

"An Account of the Invention of Friction Matches," John Walker, Stockton-on-Tees, 1909; "The True History of the Invention of the Lucifer Match," John Walker, Heavisides, Stockton-on-Tees, 1927; see also Clayton, Chem. News, 1911, 104, 223; "The Match Industry," Dixon, London, 1925; "Guide to Bryant and May's Museum Simpkin and Marshall, London; see also Gore, Chem. News, 1861, 4, 16, 31, etc.

Allied to the match industry is the use of phosphorus as a constituent of fireworks, thus :—

White Fire.—Potassium nitrate 100 parts, amorphous phosphorus 10 parts.
Blue Fire.—Potassium nitrate 500 parts, barium carbonate 300 parts, aluminium powder 200 parts, amorphous phosphorus 5 parts.
Red Fire.—Strontium nitrate 500 parts, strontium carbonate 300 parts, aluminium powder 200 parts, amorphous phosphorus 5 parts.

Firework and match materials are all potentially explosive, and should be mixed with care and in small quantities only.

Alloys with Phosphorus

Phosphorus as a constituent of bronzes is chiefly valued for its deoxidising effect, which confers a great toughness on the metal. The principal alloys are those containing copper, tin, zinc, nickel, lead and antimony. The phosphorus is usually added in the form of phosphor-tin. Phosphor-coppers may be made by heating copper phosphate or copper turnings and phosphorus in crucibles at 600-800°. Phosphor-bronze may contain Cu 89, Sn 11 and P 0.3 per cent. The phosphorus should not exceed 0.6 per cent.

Miscellaneous Uses

Calcium phosphide is used in marine signal lights, which are so constructed that they evolve spontaneously inflammable phosphine when thrown into water.

Phosphides have been used to give a conducting surface to plaster moulds for electroplating. The mould is dipped in a solution of copper sulphate, then, after drying, in a solution containing caustic potash and phosphorus from which phosphine is being evolved. Copper phosphide is precipitated on or below the surface of the plaster. In silver plating a slightly different procedure is employed. The plaster mould is first covered with wax, then dipped in a solution of phosphorus in four times its weight of carbon disulphide. It is then exposed to the air until fuming begins, whereupon it is dipped in a solution of silver nitrate containing about 100 grams of silver to the litre.

In the manufacture of tungsten lamps the tungstic oxide may be reduced by heating with yellow or red phosphorus in an atmosphere of hydrogen. The tungsten powder containing phosphide which results is suitable for drawing into the filaments.

Physiological Action of Phosphorus

Phosphorus in oil or emulsified in fat and chalk has been used in medicine, but appears to have no particular value. However, a preparation made by exposing finely divided iron to the vapours of smouldering phosphorus is useful as an application to wounds caused by corrosive concentrated carbolic acid.

The small doses of phosphorus which have occasionally been prescribed have the effect of thickening the spongy tissue of bone by the deposition of true bone. Another effect is to stimulate metabolism, leading to increased secretion of nitrogen as ammonium salts of lactic and ketonic acids, which result from the incomplete oxidation of fats and glycogen. Some of the unoxidised fat is deposited in the liver and muscles and leads to degeneration of these.

When taken internally in quantities from grains upwards, white phosphorus is an acute poison, producing at first symptoms of nausea and pain, which subside for a while, and are then succeeded by jaundice and finally coma. This action is due to the fact that phosphorus prevents the complete oxidation of glycogen and fat. In cases of violent internal poisoning the stomach-pump is used, followed by copper sulphate in amounts sufficient to cause vomiting, then oil of turpentine. Black coffee is also recommended, and also the application of mustard plasters.

The poisonous action of the vapour of phosphorus, or that of its lower oxide, is probably due to attack on exposed bone, e.g. in decayed teeth. It produces necrosis, which spreads inwards and gives rise to the disease known as "phossy jaw," which has been found among workers in factories where phosphorus was made or used. Apart from the effect on bones, the vapour does not appear to be poisonous in small amounts.

Hypophosphites and phosphates, e.g. calcium hypophosphite and glycerophosphate, are used in considerable quantities as " patent medicines " and in medicine generally as accessory foods. Acid phosphates are used extensively in baking powders and various manufactured foods. From their intimate connection with life it will be gathered that by far the most important use of phosphorus compounds is in the manufacture of fertilisers.
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