SECT. i. NON-METALLIC SIMPLE SUBSTANCES. 17 



tendencies to act chemically being increased like those 

 of ozone. That this black tenacious substance is chemi- 

 cally the same with common sulphur there can be no 

 doubt, for when it is exposed to greater heat, it again 

 bscames a colourless pellucid fluid, which thrown into 

 water resumes the form of brittle yellow sulphur. 



These new arrangements among atoms of the same 

 kind show that the immutability of matter is not 

 without exceptions. 



The animal kingdom is the great reservoir of phos- 

 phorus, a simple substance that is never found un- 

 combined. It is sparingly met with in the vegetable 

 kingdom, and still less in the mineral, but may be pro- 

 cured abundantly from calcined bones. When pure it 

 is colourless, transparent, solid, extremely poisonous, 

 and so inflammable that it must be kept in water. 

 In air it is in continual combustion with oxygen, during 

 which ozone is produced. When burnt in a current 

 of air phosphorus leaves a residuum consisting of two 

 substances, of which one is an acid, the other is redl ^ 

 allotropic phosphorus, which has been extensively used 7 

 in the manufacture of lucifer matches, because its fjameg^ -yLJt- 

 are not deleterious, and because it inflames less easily 

 than common phosphorus, to which it is reduced by heat 

 or friction, which generates heat. 



Silicon is a simple substance, never found alone, but 

 when forty-eight parts of it are combined with fifty- 

 two parts of oxygen gas it forms rock crystal, the purest 

 form of silica or quartz. Silica is so abundant that it 

 maybe said to constitute the basis of the mineral world. 

 The sand on the sea-shore, which is the debris of quartz 

 rocks, shows how universally it prevails. It is even 

 abundant in the vegetable kingdom, giving strength to 

 the stalks and leaves of the grasses, and may be felt in 

 the harshness of the beards of wheat and barley. Silicon 

 VOL. i. * c 



