FLAME. 227 



portion within the flame will lose its coating of oxide, 

 while the exterior portions at the same time become 

 more deeply oxidized, and consequently, darker colored. 

 It is because there is an excess of carbon arid hydro- 

 gen in the interior of the flame, to take oxygen from 

 the metal, by their superior affinity, and pass off with 

 it as gas or vapor. In the outside, on the other hand, 

 there is an abundant supply of air to impart oxygen, 

 or, in other words, to oxidize. By moving the coin to 

 and fro after it is once thoroughly heated, the instanta- 

 neous conversion of metal into oxide, and oxide into 

 metal, may be readily observed. A beautiful play of 

 colors, like those upon a soap bubble, will be found to 

 attend the transformation. The flame of a spirit lamp 

 is, in some respects, preferable for this experiment. 



563. OXIDIZING FLAME. The blue en- 



What is the 



oxidizing velop of the flame, which, with the hot 

 air adjacent, has the property of oxidizing 

 metals, is called the oxidizing flame. 



564. REDUCING FLAME. The body of 

 What ift the _ J 



reducing the flame, which, with the heated gas 



flame ? within it, has deoxidizing effects, and re- 



duces oxides again to the metallic form, is called the 

 reducing flame. The process of deoxidizing is called 

 reduction. 



565. THE BLOW-PIPE. The peculiar 

 effects of both the oxidizing and reducing 

 simple con- flame, may be still better obtained, by help 



ftructton. 



of the simple mouth blow-pipe. In want 

 of a metallic tube, a common tobacco-pipe, to the bowl 



