12 



17- 



The carbon or soot on 

 the glass. 



Let US see what was burning when the candle was hghted, 

 besides the oxygen in the air. Rehght the candle and hold the 

 porcelain or glass about an inch above the bright part of the 

 flame. 



Qiies. What happens to it there ? 



Next lower it directly into the flame. (Fig. 17.) 



Q21CS. What is the black stuff that gets onto the glass ? 



Look closely and see whether it is not 

 deposited here also as a fine powder. 



Qties. Will this deposit from the candle 

 blacken the fingers ? 



Instead of using the name charcoal for 

 this black substance, let us call it carbon 

 (represented by C), the better name, be- 

 cause there are several kinds of carbon, 

 and charcoal is only that kind which is 

 rather light and easily blackens the hands. 

 Some other kinds are the diamond, coal and the black substance 

 in lead pencils. This last kind is called graphite. These are 

 all much harder than charcoal. 



The carbon from the candle flame came mostly from the wax 

 or tallow ; only a very small portion came from the wick. 



It cannot be seen in the tallow, neither can it be seen in un- 

 burned wood, and yet it can be found when the wood is partly 

 burned. The condition in which the carbon exists in the tallow 

 or wood may be explained in a later lesson. At present it 

 suffices that it is there. 



Why, now, is the glass blackened when held in the flame and 

 not when held just directly above it ? It is because the carbon 

 from the candle has not been completely burned at the middle 

 of the flame ; but it is burned beyond the bright part of the 

 flame. When the glass is held in the flame, the carbon that is 

 not yet completely burned is deposited on it, because it is cooler 

 than that in the surrounding flame. 



A fine deposit of carbon can be had from any of the luminous 

 parts of the flame ; and it is these thousands of little particles of 

 carbon, getting white hot, which glow like coals in the stove and 



