24 LESSONS ON CHEMISTRY. 



Its presence, however, as we have stated, is indispensable far 

 the support of life and flame (6). Thus, in the diluted state 

 in which it exists in the air of our rooms, it gives our fires 

 and candles the power to burn ; by its influence the coal is 

 slowly consumed, giving a comfortable warmth to our dwell- 

 ings, and the tallow and the wax of our candles gradually 

 burn, affording us a cheerful light. But when a candle or 

 other ignited body is introduced into a vessel of pure undi- 

 luted oxygen, all the energy of its properties is displayed, 

 the candle no longer burns quietly as in common air, and 

 even though extinguished before being introduced, if a par- 

 ticle of its wick continues to glow, it will immediately burst 

 into a vivid flame and be rapidly consumed. Even metallic 

 bodies, which hke iron are merely melted when exposed to 

 our most intense fires, if heated in a vessel of this gas, burn 

 with brilliant sparks. 



8. When the oxygen gas which for a time supported the 

 flame of a taper in the bottle of air is consumed (6 c), four- 

 iifths of the latter remain behind, invisible like the air 

 itself, but deprived, as we have stated, of those properties 

 which render it capable of supporting flame and animal 

 life. This substance, which forms the great bulk of the air, 

 consists nearly altogether of a gas termed Nitrogen, which 

 though incapable of supportmg life when separated from 

 oxygen, yet is one of the most essential ingredients of the 

 flesh of animals, and of all those vegetable productions which 

 serve as nutritive food.* Without the presence of some 

 substance containing it, no plant could arrive at maturity, 

 or produce any of those matters in their roots and seeds 



* Nitrogen gas may be prepared by igniting a small piece of 

 Phosphorns placed in a little cup, standing on a soup-plate half filled mth 

 water, and covering it with a confectioner's jar, or wide-mouthed bottle 

 {Fig. 3). The burning Phosphorus miites with the oxygen of the air 



contained in the bottle, and the com- 

 pound formed (a substance termed 

 phosphoric acid) dissolves in the 

 water contained in the plate, leaving 

 the nitrogen gas of the air. liike 

 oxygen, nitrogen is devoid of taste, 

 smell, or colour. That it is neither 

 inflammable nor capable of support- 

 ing flame, may be shown by intro- 

 ducing a lighted candle into the 

 ~Fig^2. bottle. It is rather lighter than air. 



