PHO 



PHY- 



PHOSPHORUS (from ,f,ur, light, 

 and <pepu, I carry). "So called from its 

 property of shining in the dark : it is 

 extracted from bone eartti. Tlie 

 bones are calcined, so as to destroy 

 the animal matter, and, bcinj? pow- 

 dered, are mixed with water, to which 

 half their weij^ht of sulphuric acid is 

 added. The bone earth, consisting 

 chiefly of phosphate of lime, is thus 

 decomposed, sulphate of lime is form- 

 ed, and phosphoric acid is evolved ; 

 or, rather, superphosphate of lime, 

 which, being much more soluble than 

 the sulphate, remains in the liquid, 

 and may be obtained by its evapora- 

 tion. It is mixed with about half its 

 weight of charcoal, and put into a 

 well-luted earthen retort, the beak of 

 which dips into water. At a bright 

 red heat the phosphorus distils over 

 into the water. It is purified by care- 

 fully melting it under water, and 

 straining it through a piece of cha- 

 mois leather. 



" Pure phosphorus is an element 

 almost colourless and semitranspa- 

 rent ; it may be cut with a knife, and 

 its surface has a waxy lustre. It fu- 

 ses at 108°, boils at 550-^, and is con- 

 verted into vapour, having, accord- 

 ing to Dumas, a density = 4-35. It 

 is sparingly soluble in fixed and vola- 

 tile oils, and in ether and alcohol ; 

 but insoluble in water. It shines in 

 the dark, and emits a luminous va- 

 pour, undergoing a slow combustion, 

 and exhaling a peculiar smell like 

 garlic. When rubbed, or heated to 

 a temperature of about 1 10 % it takes 

 fire and burns with great rapidity, 

 with a white flame, emitting abun- 

 dajice of acid fumes of phosphoric 

 acid. 



" The product of the perfect com- 

 bustion of phosphorus is phosphoric 

 acid, a fusible substance, very solu- 

 ble in water, and intensely sour. It 

 appears to consist of 1 equivalent 

 of phosphorus = 31-44, and 5 of 

 oxygen = 41, its equivalent being 

 7144. 



" There are two other acids of phos- 

 phorus, namely, the phosphorous acid, 

 consistmg of 31 44 phosphorus -\- 24 

 oxygen, and the hypophosphorous 

 576 



[ acid. When phosphorus is boiled in a 

 ! solution of caustic potash a gas is 

 evolved, which is remarkably distin- 

 guished by its spontaneous inflamma- 

 bility, each bubble, as it rises through 

 the water, taking fire upon the sur- 

 face and producing a beautiful ring of 

 smoke : this gas is commonly called 

 phosphuretted hydrogen. Phospho- 

 j rus may be made to combine with the 

 greater number of the metals, form- 

 i ing compounds called phosphurets." 

 I Phosphorus is not found in the ele- 

 mentary state in nature, but in the 

 : form of phosphoric acid it is combi- 

 I ned with lime, magnesia, alumina, 

 and many metals, forming native 

 phosphates. Most of these are insol- 

 I uble in pure water, but dissolve in 

 ! acids and in carbonic acid water. In 

 this solution they are carried to plants, 

 which have the property of decompo- 

 sing them, and assimilating the phos- 

 phorus. Fibrin, albumen, some oils, 

 and other products of vegetation, con- 

 tain phosphorus. It is to all vegeta- 

 tion an essential body, especially for 

 the production of seeds. Bone earth, 

 ' or phosphate of lime, is the principal 

 j source for manure ; but urine, and 

 i the dung of all animals, contain phos- 

 I phates. 



I It is frequent to see a distinction 

 made between phosphoric, metaphos- 

 phoric,and pyrophosphoric acids ; but 

 ; these have all the same basis, the 

 phosphoric acid being tribasic, and 

 forming three sets of salts with some 

 bodies which are different in charac- 

 [ ters. 



I PHOTOMETER (from i>ojc, and 

 I fjcTpov, a measure). An instrument 

 to measure the intensity of light. 



PHRENITIS. Inflammation of the 

 brain. 



PHRYGANID-E. Tricopterous in- 

 sects, case-worm flies. 



PHYCOMETER. The gelatinous 

 matter in which the sporules of the 

 lowest plants germinate. 



PHYLLODIA. Leaves in which 

 the petiole is very much expanded 

 and the lamina absent. 



PHYSICS. Mechanical philoso- 

 phy. The study of the properties of 

 objects and their motions. 



