[273] A hound took 200 grms. of red phosphorus in twelve days, and remained healthy.--Sonnenschein. [274] Schrotter, _Chem. News_, vol. xxxvi. p. 198. § 273. =Phosphuretted Hydrogen.=--=Phosphine= (PH₃), mol. weight 34, specific gravity 1·178, percentage composition, phosphorus 91·43, hydrogen 8·57 by weight. The absolutely pure gas is not spontaneously inflammable, but that made by the ordinary process is so. It is a colourless, highly poisonous gas, which does not support combustion, but is itself combustible, burning to phosphoric acid (PH₃ + 2O₂ = PO₄H₃). Extremely dangerous explosive mixtures may be made by combining phosphine and air or oxygen. Phosphine, when quite dry, burns with a white flame, but if mixed with aqueous vapour, it is green; hence a hydrogen flame containing a mixture of PH₃ possesses a green colour. If sulphur is heated in a stream of phosphine, hydric sulphide and sulphur phosphide are the products. Oxides of the metals, heated with phosphine, yield phosphides with formation of water. Iodine, warmed in phosphine, gives white crystals of iodine phosphonium, and biniodide of phosphorus, 5I + 4PH₃ = 3PIH₄ + PI₂. Chlorine inflames the gas, the final result being hydric chloride and chloride of phosphorus, PH₃ + 8Cl = 3ClH + PCl₅. One of the most important decompositions for our purpose is the action of phosphine on a solution of nitrate of silver; there is a separation of metallic silver, and nitric and phosphoric acids are found in solution, thus--8AgNO₃ + PH₃ + 4OH₂ = 8Ag + 8HNO₃ + PO₄H₃. This is, however, rather the end reaction; for, at first, there is a separation of a black precipitate composed of phosphor-silver. The excess of silver can be separated by hydric chloride, and the phosphoric acid made evident by the addition of molybdic acid in excess. § 274. =The medicinal preparations of phosphorus= are not numerous; it is usually prescribed in the form of pills, made by manufacturers of coated pills on a large scale. The pills are composed of phosphorus, balsam of Tolu, yellow wax, and curd soap, and 3 grains equal 1/30 grain of phosphorus. There is also a _phosphorated oil_, containing about 1 part of phosphorus in 100; that of the French Pharmacopœia is made with 1 part of dried phosphorus dissolved in 50 parts of warm almond oil; that of the German has 1 part in 80; the strength of the former is therefore 2 per cent., of the latter 1·25 per cent. The medicinal dose of phosphorus is from 1/100 to 1/30 grain. § 275. =Matches and Vermin Pastes.=--An acquaintance with the percentage of phosphorus in the different pastes and matches of commerce will be found useful. Most of the vermin-destroying pastes contain from 1 to 2 per cent. of phosphorus. A phosphorus paste that was fatal to a child,[275] and gave rise to serious symptoms in others, was composed as follows:-- [275] Casper’s 204th case.