230 THE CHEMISTRY OF CREATION. 



serve repetition. Since charcoal itself is quite 

 insoluble, its effects are, in all probability, due 

 to the ammonia it condenses from the air. It 

 must, however, be added, that it is highly de- 

 sirable that experiments of a satisfactory kind, 

 as to extent and character, should be made upon 

 this subject. 



It will now be useful to sum up the normal 

 constituents of the atmosphere from the pre- 

 ceding observations. The atmosphere consists 

 primarily of two gases, four-fifths being nitro- 

 gen, and one-fifth oxygen ; but, in addition, 

 and to adapt it for the purposes of vegetation 

 and ultimately for the supply of the very con- 

 ditions of human and animal existence, it con- 

 tains, in small proportions, two ingredients, the 

 use of which is well ascertained ; and a third, 

 upon which some question still remains. The 

 two first are carbonic acid and ammonia ; the 

 last is carburetted hydrogen. The following 

 table will represent in a more satisfactory man- 

 ner what the chemist could find if he were to be 

 at the pains to analyse ten thousand volumes of 

 dry air : 



Nitrogen 7,912 



Oxygen 2,080 



Carlxmic acid 4: 



Carburetted hydrogen ... 4 

 Ammonia traces 



10.000 





