GASES 



155 



to find out that it is a gas flame, the brilliant light being pro- 

 duced by minute particles of carbon becoming incandescent as 

 they pass from the central portion, where no combustion is going 

 on, thru the part lying just outside of this where the gases are in 

 active combustion. The gases which burn and the carbon which 

 thus makes the light and is finally consumed, are all from the oil of 

 the candle being decomposed into these products by the heat, 

 just as the same products are made out of coal by heat in the 

 process of the manufacture of illuminating gas, and in the mak- 

 ing of gas out of wood in the experiments already given. None 

 of these facts is to be told at first. 



By cutting a few candles in- 

 to short pieces each pupil can 

 have his own flame to study. 



Let each try to make out the 

 parts of the flame (fig. 82). It 

 will be found that there are four: 

 the blue cup at the bottom; a 

 thin, almost transparent outer 

 sheet of flame; a brilliant light- 

 giving part just underneath this; 

 and a dark central portion. In 

 the dark central portion is a 

 mass of gases charged with black 

 floating particles of carbon 

 (smoke). If a sheet of paper held 

 horizontally is suddenly thrust 

 down on the flame to about its 

 middle and held for a short time, 

 but removed just before it breaks 

 into a flame, a round ring is 



i -i ,-> 



SCOrched Oil the paper COrrCS- 



ponding to the two outer coats 



Fig. 82. candle flame showing the four 



parts described in the text, also showing 

 the method of introducing a small tube 



