AMMONIA IN THE AIR. 221 



which are the natural gaseous springs before 

 alluded to. It is also a product of the decay of 

 vegetable tissues, and is largely thrown into the 

 air from the countless economical processes con- 

 nected with human operations. 



Who that has looked with grateful surprise 

 on his fields a few days since parched and 

 brown, now re-clothed with raiment of freshest 

 green, the herbage springing up with that 

 vigour and luxuriance peculiar to the growth 

 of the tender blade, when the " clear shining of 

 the sun follows rain," would suppose that this 

 sudden verdure owed anything to Ammonia? 

 Still less would one be disposed to admit that 

 our pastures are deeply indebted to a gaseous 

 constituent of the air, so minute in its amount, 

 as we shall learn, as to have long eluded the 

 search of the most eminent chemists. Am- 

 monia had long been suspected to exist in the 

 air. Philosophers, aware of the numerous 

 sources from whence this volatile compound was 

 disengaged, felt persuaded of its presence in the 

 atmosphere, but -were unable to confirm their 

 suspicions. At length, Liebig conceived the 

 happy idea of trying whether it might not be 

 found in rain-water. Since ammonia is very 

 soluble in water, it seemed rational to suppose 

 that if it really existed in the air, it would be 

 found in the waters of a shower. A consider- 



