Phosphuretted Hydrogen Gas (PH,).—This gas was obtained by Oengcmbre in 1783: it is procured by boiling phosphorus in a solution of potash, or in small quantity on bringing phosphide of calcium into contact with water. The gas which arises is spontaneously inflam mable; and during its combustion there are formed water and phos phoric acid : it is colourless, and has a disagreeable odour resembling that of onions. Water dissolves about two per cent. of this gas ; but the solution, unlike that of sulphiiretted hydrogen gas, has no acid properties. It deposits solid phosphuretted hydrogen when exposed to light. The specific gravity of this gas, according to Dumas, is 1161. Its spontaneously inflammable property is due to the presence of liquid phosphurctted hydrogen (PH,). The latter may be separated by passing the freshly-made gas through a tube immersed in a freezing mixture. It burns explosively when exposed to the air, and renders hydrogen, carbonic oxide, &c, spontaneously inflammable.
Phosphuretted hydrogen gas decomposes some metallic solutions, such as those of copper and mercury, and metallic phosphides are pre cipitated. When it is pure, it is entirely absorbed by sulphate of
copper and chloride of lime.
Chlorine and Phosphorus combine in two proportions, forming the pcntachloride and terchloride.
Terchloridc of Phosphorus (PCI,).—Whcn a mixture of bichloride of mercury and phosphorus is heated, we have already had occasion to notice that terchloride of phosphorus is produced. When first pro cured, it has generally a reddish colour, owing to the presence of a little uncombined phosphorus. When this has had time to deposit, or when it is purified by slow distillation, it becomes limpid and colour less. It has a suffocating odour, and fumes when exposed to the air. Its specific gravity is 1'616. It dues not alter the colour of dry litmus paper ; but if moist, then hydrochloric and phosphorous acids are formed, which redden it strungly. The vapour of this compound is combustible, and acts with great energy upon water, producing the changes which have been described.
Pentculdoride of Phosphorus is obtained by the spontaneoue