SOURCES OF OXYGEN. 213 



question that a most serious deficiency of this 

 gas would have been sensible at this period of 

 the earth's history. The Chemistry of Creation, 

 however, informs us that a never-failing spring 

 of oxygen exists, and its copious streams, by a 

 nice adjustment, replace by far the greater part 

 of the loss. In this green grass, in the leaves 

 of these unpretending herbs, and in those of 

 the clustering wood, we shall hereafter find are 

 hid those springs of this precious ingredient of 

 our air, without which desolation and death 

 might at no distant time gradually overwhelm 

 our globe. 



From the preceding remarks, it must not be 

 supposed that the atmosphere is purely a mix- 

 ture of two gases. Such we may indeed truly 

 consider as the composition of air, but by no 

 means that of our atmosphere. Oxygen and 

 hydrogen in chemical union form water, but 

 pure water would ill satisfy the wants of the 

 countless inhabitants of the ocean. So, while 

 we may justly regard oxygen and nitrogen 

 in the given proportions as air, the atmosphere 

 would be totally unfitted to fulfil its present 

 functions, were there no other gaseous ingre- 

 dients present in it. Indeed, the salts and 

 dissolved gases of the great deep do not stand 

 in anything like the same relation of importance 

 to the tribes which people it, as does the admix- 



