4 THE CHEMISTRY OF WATER. 



The chemical affinity between these two elements- 

 air and water (if we may, for the sake of convenience, 

 be permitted to call them so) concerning w r hich we 

 desire to say a word in passing, is also not a little 

 remarkable. 



Atmospheric air, as most of us are aware, is merely 

 a mechanical admixture of nitrogen and oxygen gases, 

 in the proportion of about four of the former to one 

 of the latter, by volume (among chemists this is usually 

 expressed by the symbol o + N ) ; while water is 

 formed by the chemical combination of oxygen and 

 hydrogen, in the proportion of two volumes of hydrogen 

 to one of oxygen (the symbol therefore by which it 

 is now expressed is H2O). 



The mixture, however, of hydrogen and oxygen 

 gases does not form water; but upon the explosion 

 or combustion of pure hydrogen gas in the air, the 

 product is water, through the consequent instantaneous 

 combination of the oxygen of the atmosphere with the 

 hydrogen; the nitrogen contained in so much of the 

 air as is thus "consumed," or converted into water, 

 being given off in the form of pure nitrogen gas. 

 We have allowed the word " consumed " to stand (as 

 above) with a view to recall that great maxim (which 

 should always be present to our minds when dealing 

 with questions of chemistry, or other natural phenomena) 

 that though we may for convenience sake speak 

 of a thing as ostensibly " consumed " (as for instance 

 in the case of a candle that is burnt out), yet nothing 

 is in reality consumed or destroyed in Nature: but 



the whole of the water falling upon the earth, is returned directly to 

 the ocean: the remaining -^ falling upon the land (Encycl. Brit., 9th 

 edit., Vol. xxiv., p. 398 [Art. "Water"]). 



