PHOSPHURETS. 441 



In these cases water is decomposed ; its hydrogen, with a portion 

 of phosphorus, forms phosphuretted hydrogen, and its oxygen, with 

 other proportions, forms phosphorous, and hypo-phosphorous acid. 



2. PROPERTIES. 



(a.) Smell alliaceous ; fires spontaneously, with a beautiful ring of 

 smoke, rising and enlarging for some distance ; it is vapor of water 

 and phosphorous acid ; similar appearances are sometimes seen dur- 

 ing the discharge of artillery. 



(b.) Detonates with oxygen, 1^ of oxygen to 1 measure of phos- 

 phuretted hydrogen ; only one bubble of either gas must be let up 

 into the other at once. The combustion is very brilliant.* If only 1 

 measure of oxygen be used, the product is phosphorous acid, if 1 J, 

 it is the phosphoric. 



(c.) In chlorine and nitrous oxide gases, phosphuretted hydro- 

 gen explodes. In all these cases, the same effect is produced, if 

 the gas supporting combustion be let up into the phosphuretted hy- 

 drogen, and with oxygen this course is rather safer. 



(d.) Sulphurous acid gas, and phosphuretted hydrogen mutually 

 decompose each other. 



(e.) Phosphuretted hydrogen loses its spontaneous inflammability, 

 after standing a short time ; a part of the phosphorus is deposited ; 

 but it still burns, and with a very bright light, when kindled by a candle. 



(/.) In the dark, and over mercury, it retains its inflammability a 

 long time. 



(g.) It is lighter than common air. Air being 1, its sp. gr. is ac- 

 cording to Thomson, .9027, theory and experiment coinciding, for 

 sp. gr. of hydrogen, - 0.0694 



And of phosphorus vapor, 0.8333 



0.9027f 

 Dumas gives it at 1.761 5 Dalton at 1.1. 



* A, represents an air jar, with a few cubic 

 inches of oxygen gas, standing over a column of 

 water. B, is a retort, with slacked lime, phos- 

 phorus, and strong solution of pearl ashes, the 

 bubbles of gas coming singly, but rather rapid- 

 ly on depressing the mouth of the retort, (on 

 a particular occasion,) a little gas accumulated, 

 and one bubble hung in the glass jar without 

 explosion, but the next blew up the whole 

 with great violence, broke all the contigu- 

 ous glass vessels, shot some of their fragments 

 to the distance of 40 feet, among a large au- B 

 dience, and slightly wounded several specta- 

 tors ; this shews the necessity of extreme 

 caution. See Am. Jour. Vol. VI, p. 187. 



t Henry, Vol. 1, p. 489. 



56 



