56 CHEMISTRY. 



be introduced into a jar filled with oxygen, it will burn 

 much more briskly and brilliantly than in the air. For the 

 same reason, if a candle or taper be blown out, it will 

 at once be rekindled if put into ajar of oxygen, though 

 there be only a slight spark on the wick. This may 

 be done many times in the same jar of oxygen. After 

 a while this effect will not be produced, because the 

 oxygen is used up ; for every time the candle is in- 

 troduced some of the oxygen unites with the wick 

 and the tallow. It is this union that produces the 

 phenomenon which we call combustion. A very con- 

 venient way of introducing a taper or a candle into 

 .r. j ars filled w jth gas is represented in Fig. 7. 



57. Charcoal Burned in Oxygen. If a piece of charcoal 

 be ignited in the air, it will exhibit only a dull red color ; 

 but the moment that it is introduced into oxygen gas it 

 burns brilliantly, casting off sparks with great rapidity, as 



seen in Fig. 8. Charcoal made from bark is 

 better for this experiment than that made from 

 wood. In this case, as in that mentioned in 

 56, the oxygen is used up by uniting with 

 the burning substance. In doing this it forms 

 with the charcoal or carbon carbonic anhy- 

 dride, a gas which we shall speak of particularly in the 

 next chapter. This union is very simple : C + O 2 =CO 2 . 



58. Phosphorus Burned in Oxygen. One of the most 

 splendid experiments with oxygen is the burning of phos- 

 phorus in it. On introducing the ignited 

 phosphorus into a vessel filled with oxygen, 

 Fig. 9, thick white fumes arise, illuminated 

 by a most intense brightness. In the combus- 

 tion here the oxygen unites with the phospho- 

 rus to form phosphoric anhydride, the parti- 

 Fig. 9. cles of which make the fumes that you see. 



In this case we have P 2 +O 3 =:P 2 O 5 . 



