PHOSPHORESCENCE 



it; i: 



PHOSPHORUS 



HIM Is. When crops are product <1 year after year 

 on rhr .-.HIM- .-oil the natural supply of pho 

 ph:it-s i.- gradually removed, ami artificial fer- 

 tilizing by means of manure becoi -dry. 

 Phosphate rock is the chief source of fertilizer 

 containing phosphates. By eru.-lung tin- rork 



and tpating it With sulphuric acid a -ohlble 



fertilizer known as superphosphate i> made, 

 which acts much more quickly than the pulvcr- 

 i/ed ruck 



' quantin.- Hi' fertilizing phosjih r 

 found in bed- of leached guano on certain i 

 lands of the Pacific, in the West Indies and in 

 Venezuela; on Christmas Island, in the Pacific, 

 there is a bed 100 feet deep yielding nearly 

 300,000 tons a year. See FERTILIZEK. 



PHOSPHORESCENCE, fox fahr cs'cna, from 

 the Greek phos, meaning lit/lit , and phoros, 

 bringing light, the emission of a pale, sometimes 

 ill-defined. light, by bodies possessing the 

 quality of becoming self-luminous after \- 

 posure to light. It does not have its origin in 

 combustion. The substance in which this pe- 

 culiarity was first noticed was barium sulphide. 

 the discovery of a Bologna shoemaker in 1602. 

 It was quickly found that there were many 

 other bodies to be added to the list. The an- 

 cients knew that a diamond when slightly 



d became phosphorescent, and Pliny men- 

 tions other gems which cast off a light of then 

 own when in darkness. The color of the phos- 

 phorescent light is influenced by the kind of 

 light to which the substance has been exposed, 

 and varies with the nature of the substance. 



r being exposed to sunlight, calcite gives an 

 orange light, while argonite give- a green light 

 under the same circumstances. 



Phosphorescence must not be confused with 

 the luminosity of phosphorus. The light com- 

 ing from phosphorus is caused by oxidation and 

 not depend on previous exposure to light, 

 while phosphorescent* i- the direct result of 

 such exposure. The application of heat will 



cause MMne .-tibstalice- to become lumiliou- m a 



darkened room; in some cases, notably with a 



ty of fluorspar, the heat of the hand i- 

 lent, but every case demands previou 



posure to light 



imente have proved that there are a 



' number of substances which become self- 

 luminous after exposure to light, m -.inn cases 



phosphorescence lasting only ih. n ft ion 

 of a second, in others lasting for days. Me- 



:< d ipphalic. -ed to d> 



Rid) -ln.it diirahoi. 

 mvi-ible to the hum. in \ It h II d-o been 



shown that the vividness and duration of phos- 

 phorescence of many sub-t; ; < dly cal- 

 cium sulphide. dep nd on the pn.-ence in that 

 substance of impurities, such as manganese, 

 bismuth and copper. Gelatin, celluloid, paraffin 



and ivory are phosphorescent at v IN low tem- 

 peratures', while certain other sub-taiice- ;,,-,. 

 phosphorescent only when subjected to friction. 



The most interesting cases of phosphores- 

 cence occur in the animal world, the luminous 

 property belonging to nearly every main group 

 of the zoological series. Phosphorus being 

 highly poisonous to all animal tissues, it is ap- 

 parent that it can play no part in animal lumi- 

 nosity. In some of the lowest forms of life the 

 whole body is phosphorescent, as in the case 

 of the jelly fish. In other organisms, such as 

 the firefly and glowworm, the luminosity i- 

 localized and produced by a highly efficient but 

 minute mechanism. Whether phosphoresc 

 is attractive or protective is a matter of con- 

 ure, though it is commonly supposed that 

 in the case of the firefly the luminosity jfl 

 signed to attract. Probably in some i; 

 life phosphorescence indicates the presence of 

 disease. The great displays of phosphores< 

 in sea water are due to the presence of in- 

 numerable phosphorescent organisms and are 

 not derived from the water itself. F.ST.A. 



PHOSPHORIC, losfahr'ic. ACID, an acid of 

 phosphorus made by dissolving the whin 

 por formed by burning phosphorus in air or 

 oxygen in water. It may also be produced by 

 treating yellow phosphorus with dilute nitric 

 acid and evaporating the solution, when it 

 forms in colorless crystals. Phosphoric acid 

 enter* into all the compounds known as phos- 

 phates, -ome of winch have a wide range pi 

 fulness. See PHOSPH m:s; Piiosrtioi<i - 



PHOSPHORUS, fo'jahru. The aneieni 



Greeks were acquainted with a yellou. | 

 .-nbstance that glowed in the dark, which they 

 named light heart r. The Creek words for tin- 

 name when united form the word plios^i,- 

 Common phosphorus is a yellowi.-h. \\a\like 

 -ub-t.infe ihai ha- the odor of a burning match 

 When exposed to the air in a dark room it 

 glows, or is phimphnnsci nt. It burns at or- 

 din ratures, and melts at about 98 F. 



Phosphoi v poisonous, and it i- unsafe 



to handle it unless it is under water. Burn- 

 from it are diflicult to heal, and a small 

 of it will cause death. Because of n- Inbilnv 

 n has to bo kept under v 



I'litll recently the chief U-e of pho-pllOHIS 



WES in the manufacture of matches (which 



