74 A YEAR IN SCIENCE 



not to breathe the fumes. Because of the rapidity, with 

 which oxygen and phosphorus unite, phosphorus emits 

 a light when exposed to air. This property is known 

 as phosphorescence. If yellow phosphorus is heated in 

 closed vessels to a temperature of 250C. to 300C., 

 its nature changes completely, producing the form 

 called red phosphorus. On further heating it under- 

 goes another change and becomes yellow phosphorus once 

 more. 



Red phosphorus is a dull red, powdery substance, 

 very inactive and perfectly safe to handle. It does not 

 give off a light as does the yellow phosphorus, neither 

 is it poisonous. 



Uses of phosphorus. Because of its poisonous nature 

 yellow phosphorus is used in preparing poison for rats, 

 mice, and other vermin. Its chief use, however, as well 

 as that of the red phosphorus, is in the manufacture of 

 matches. 



Friction match. In preparing the common friction 

 match, the end of the stick is soaked in a mixture 

 usually containing paraffin, sulphur, phosphorus, glue, 

 and some compound containing a great deal of oxygen. 

 On striking the match the heat produced from the fric- 

 tion kindles the phosphorus, which unites with the 

 oxygen in the compound on the head of the match, and 

 also with the oxygen in the air. The sulphur and 

 paraffin are then ignited, and their burning sets fire 

 to the wood. 



Safety match. The safety match differs from the 



