THE ATMOSPHERE. 



this gas unmixed with any other substance, it will be in- 

 stantly relighted. Many substances will burn in this air 

 in a pure state, which will not in common air. If iron be 

 heated and immersed in pure oxigen, it will instantly 

 melt and burn, throwing its particles in every direction, 

 with an intense and brilliant light. Consequently, if the 

 oxigen of the atmosphere were not diluted or weakened 

 by another kind of air, stoves, andirons, and numerous 

 other instruments made of iron, would melt and be con- 

 sumed the instant they were raised to a high heat. Al- 

 most everything would be combustible, and the earth 

 would soon present one great and general conflagration. 

 How wise and how good, then, is the Creator of the atmos- 

 phere, not only in furnishing it with oxigen to support 

 life and combustion, but in diluting it with another sub- 

 stance, to prevent its destroying every living being upon 

 the earth, and the earth itself! 



III. Oxigen carries on fermentation. Without it, 

 neither cider, beer, wine, or even yeast, or light bread, 

 could be formed. Almost all animal and vegetable sub- 

 stances are liable to ferment, and, consequently, to waste 

 with decay. 



Wherever we witness this process, we may know that 

 the same agent is present and employed, as conducts res- 

 piration and combustion. 



Numerous substances undergo four evident and distinct 

 changes by the power of this agent. These four changes, 

 to which nearly all animal and vegetable matter is liable, 

 may be familiarly and clearly represented and illustrated 

 by one instance of common occurrence, and known to 

 every person. A little reflection will bring to mind four 

 changes the apple undergoes, all of which are produced 

 by oxigen. 



The first is giving it a sweet taste, or forming in it a" 

 quantity of sugar. This change takes place when apples 

 are bruised, or ground to pomace, for the making of cider. 

 A single apple, if broken into pieces, and exposed to the 

 air, will show this fact. It will soon become sweet, es- 

 pecially if the weather is warm, whatever may be its nat- 

 ural taste. The juice of the apple, when running from 

 the cider press, is always sweet, and contains sugar. This 



