2

Officinal. Phosphorus, Lond.

Syn. Phosphore (F.).

This substance was discovered by Brandt, a chemist of Hamburgh, in 1669: it was prepared from putrid urine, but the process remained a secret until 1737; and in 1769 Jahn having discovered it in bones, Scheele made public the method of preparing it which is now practised. The bones are first calcined completely, to destroy their animal matter; they are then reduced to a fine powder, and digested with half their weight of strong sulphuric acid, and a small quantity to give the whole the consistence of a thin paste. The phosphate of lime, the proportion of which is about four-fifths of the calcined bones, is thus decomposed, and a sulphate and a superphosphate of lime are formed. The former is insoluble, the latter is dissolved in hot water, and the filtered solution evaporated to the consistence of syrup: it is then mixed with one-fourth of its weight of charcoal, and strongly heated in an earthen retort luted with clay, the beak of the retort being placed under water. As the heat increases, the phosphorus first comes over in the form of a reddish brown phosphuret of carbon, and afterwards the phosphorus distils, and is condensed in the water; a second distillation renders it pure.

In this process the charcoal decomposes the acid of the superphosphate, carbonic acid and phosphorus pass over, and phosphate of lime and redundant charcoal remain in the retort. The fused phosphorus is run into moulds and formed into small cylinders.

Qualities. - Pure phosphorus is diaphanous, and almost colourless, but it usually has a yellowish hue: it is flexible, ductile, soft enough to be cut with a knife, and displays on the cut surface a waxy lustre. Its sp. gr. is 1.77. It fuses at 108, and is sublimed in vapour at 550°. It is stated to be insoluble in water; but when kept in that fluid it yields to it both odour and taste. It is partially soluble in alcohol and ether, and by the aid of heat dissolves in oils, both fixed and volatile. Exposed to the air at 60°, phosphorus undergoes slow combustion, and is converted into phosphoric acid, by from light, and to carry abstracting the oxygen of the air. A very slight degree of heat, even friction between the fingers, inflames it, and it burns rapidly. The cylinders are usually kept in water, and when exposed to light acquire a white coating, which Rose1 has ascertained to be neither an oxide nor a hydrate, but a peculiar mechanical change in the phosphorus. The equivalent of phosphorus is 157. {Turner.)

1 Owing to peculiar idiosyncrasy the smallest portion of the white of egg cannot be eaten by some persons without occasioning pain, sickness, and an erythematic emotion on the skin.

Medical properties and uses.-Phosphorus is a most powerful excitant and diuretic; and, except in small doses, operates as a poison. Its obvious effects are displayed on the generative organs, as an aphrodisiac, a fact confirmed by the experiments of Leroy and Chenevix. It has been employed on the Continent in low, sinking conditions of the habit, the result of various diseases, and in impotency. As ether diminishes the inflammability of phosphorus, the etherial solution, made with gr. iij. of phosphorus and f j. of ether2, has been chiefly employed in doses of ten drops, in any bland vehicle, repeated every second, third, or fourth hour, according to circumstances. M.,Lescot and others prefer oil as a vehicle. M. Lescot digests 3j. of phosphorus cut in small pieces in j ss. of olive oil, and after allowing the compound to stand in a dark place for fifteen days, he decants, and flavours the solution with oil of bergamot. The dose of this oil is xx to xxx in any bland mucilage. Under every circumstance, the utmost caution is requisite during the internal administration of phosphorus.

Officinal preparation.-Acidum Phosphoricum dilutum, L.