PHOSPHORUS AND ITS COMPOUNDS 



281 



offensive odour, recalling that of rotten fish, is evolved. After 

 a short time each bubble of the gas ignites directly it reaches 

 the air, forms a bright flash and a white cloud which ascends 

 as a cloud ring. Collect a jar of the gas, but do not remove 

 it from the water, pass up into it a piece of litmus paper. 

 Observe it has no action. Allow this jar to stand over water, 

 and examine the next day. It does not now ignite when exposed 



FIG. 134. Preparation of Phosphoretted Hydrogen. 



to the air, but on the application of a lighted taper burns with 

 formation of white fumes. 



N.B. Be very careful not to let the water rush back into 

 the retort, otherwise it will crack and an explosion result. 

 This is easily prevented by turning on the coal gas should 

 the water be seen ascending from any cause. 



The gas so obtained is a compound of phosphorus and 

 hydrogen, known as phosphine or phosphoretted hydrogen, and 

 represented by the formula PH 3 . This formula may be proved by 

 the decomposition of the gas by electric sparks, when it forms red 

 phosphorus and hydrogen, 2 volumes of gas yielding 3 volumes 

 of hydrogen. By the action of chlorine, also, it forms a chloride 

 of phosphorus and hydrochloric acid, which we know contains 

 hydrogen. The white fumes formed during its combustion 

 consist of a mixture of water and a compound known as meta- 

 phosphoric acid, and the equation for this action may be thus 

 written : 



PH 3 + 2O 2 = H 2 O + HPO 3 . 



Meta- 



phosphoric 



Acid. 



