226 



METALLOIDS. 



shape, without coherence. It is created by a spark, 

 and annihilated by a breath. Invulnerable itself, it 

 destroys whatever it touches. Divided and subdivided, 

 it is still the same, yet endowed with the power of re- 

 solving other materials into their elements. Chemistry 

 resolves this mystery, and gives us the satisfaction of 

 definite knowledge in its place. But, as in all similar 

 case, while satisfying the understanding, it opens new 

 fields to the imagination. The subject of combustion, 

 as involved in flame, introduces us, for example, to a 

 knowledge of the grand system of circulation of mat- 

 ter as set forth in the last chapter of this work. 



561. STRUCTURE OF FLAME. EXPLANA- 

 J5sfain the 



nifitdnre of TioN. Every lamp or candle, is 



a gas factory, in which gas is k 

 first produced out of oil or fat, by the fire 

 which kindles it, and afterward by heat the 

 of its own flame. A flame, if carefully ob- 

 served, will be found to consist of three 

 distinct parts ; a dark centre, a luminous 

 body, and a faint blue envelop. The dark 

 centre, is unburned gas. The body of the 

 flame consists of particles of carbon or lamp- 

 black, heated white hot, by the combustion 

 of hydrogen. In the exterior blue envelop, 

 the carbon particles are consumed as they 

 are crowded outwards, by the flow of newly-formed 

 gas. 



562. EFFECT OF FLAME ON METALS. 



What is the 



effect of flame If a tarnished penny be held perpendicu- 

 larly in the flame of a lamp or candle, the 



on metals ? 



