142 PRACTICAL LESSONS IN SCIENCE. 



used in the manufacture of glue. The mineral matter of the bone 

 is then subjected to distillation, from which results ammonia 

 and bone charcoal. The charcoal is used by the sugar refineries 

 until its decolorizing power has been exhausted, when it is 

 strongly hearted, burning away the carbon, leaving the bone-ash, 

 consisting largely of calcium phosphate. This bone-ash is heated 

 with diluted sulphuric acid, which forms with the lime a nearly 

 insoluble calcium sulphate, leaving phosphoric oxide, P 2 5 , in 

 solution. This solution strained and evaporated to the consist- 

 ency of sirup is mixed with charcoal and strongly heated, when 

 the oxygen unites with the carbon, and the phosphorus rising as 

 vapor is condensed in water. 



Phosphorus is a soft, yellowish, semi-transparent, waxy solid, 

 which exposed to the sunlight soon becomes darkened. It is 

 extremely inflammable, taking fire in the air by the heat arising 

 from the slightest friction. It is kept under water to protect it 

 from oxygen, and it should be kept and handled under water, as 

 the heat of the hand will cause it to burn. It not only burns in 

 oxygen and the air, but burns in chlorine, bromine, or iodine. 

 When exposed to the air it undergoes slow oxidation, giving off 

 a white vapor of a garlic odor. In the dark phosphorus gives 

 out light; hence its name, meaning bearer of light. 



If phosphorus is heated without access of air a second variety 

 called red phosphorus is formed. Ordinary phosphorus is soluble 

 in the bisulphide of carbon, is poisonous and easily inflammable. 

 The red phosphorus is insoluble, not poisonous, not easily inflam- 

 mable. The allotropic forms of phosphorus are as well marked 

 as those of sulphur and carbon, and are as yet unexplained. 



The principal use of phosphorus is the manufacture of 

 matches. Matches were invented early in the present century, 

 but the phosphorus friction match was first produced on a com- 

 mercial scale about 1832. A match consists of a splint of wood, 

 one end of which has been dipped in melted sulphur or wax, or 

 paraffine, and this substance covered with the " match composi- 

 tion," which is generally composed of chlorate of potash, phos- 

 phorus, red lead and glue. The match depends for its action 



