228 poisons: their effects and detection. [§§ 279 - 281 . 
§ 279. Phosphuretted Hydrogen.—Phosphine (PH 3 ), mol. weight 
34; specific gravity 1-178; percentage composition, phosphorus 91-18, 
hydrogen 8-82 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 (PH 3 -f-20 2 = P0 4 H 3 ). 
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 PH 3 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-j-4PH 3 = 3PIH 4 -|-PI 2 . Chlorine inflames the gas, the 
final result being hydric chloride and chloride of phosphorus, PH 3 -f- 
8Cl = 3ClH-{-PCl 5 . 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—8AgN0 3 -j-PH 3 -j-40H 2 = 8Ag-f- 
8HN0 3 -j-P0 4 H 3 . 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. 
§ 280. 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, oil of 
theobroma, wool fat, kaolin, and sodium sulphate. The phosphorus is 
dissolved, for the purpose of making the pill mass, in carbon disulphide 
and the oil of theobroma. The phosphorus content is equal to 1 per 
cent. There is also a 'phosphorated oil , containing about 1 part 
of phosphorus in 100 ; that of the French Pharmacopoeia 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 to grain. 
§ 281. Matches and Vermin Pastes. —An acquaintance with the 
percentage of phosphorus in the different pastes and matches of com¬ 
merce 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, 1 and gave rise to serious 
symptoms in others, was composed as follows :— 
1 Casper’s 204th case. 
