150 Agriadtural Chemistry. [March, 



acre of earth or soil one foot deep. If this has not come from the 

 atmosphere in rain and snow, the earth itself must be considered 

 no small reservoir of ammonia. Indeed, before Prof. Horsford had 

 found ammonia in the ice of the glacier^,, it was made certain 

 that ammonia descends by rain and snow, and hail, to the earth. 



12. Giving this extension to the doctrine of Liebig, there are 

 adequate reasons for doubting its truth, and for modifying and 

 qualifying its language. 



13. The quantity of carbonic acid is about one-thousandth of 

 the weight of the atmosphere. This is adequate, no doubt, to 

 supply all the demands of the vegetable world. It is continually 

 taken up by vegetables, or carried to the earth by the falling 

 vapor, and thus placed in a situation to be used by them. It is 

 produced by the respiration of animals, by combustion of all ve- 

 getable and animal matter, and by those chemical processes which 

 reduce organized matter to its elements. Vast quantities must be 

 produced in the last method. It is the natural result of the putre- 

 factive process in vegetable matter. This is the very condition 

 of many manures of both vegetable and animal origin. Is it con- 

 ceivable, then, that this process shall go on in the decay of vege- 

 tables, and not hold true in relation to manures? Shall carbonic 

 acid result from the natural changes of organic matter, except in 

 the case of manures'? This must surpass belief But, if this pro- 

 cess lakes place, manures must be converted, to a great extent, 

 into cai'bonic acid, which is formed in the very position to be 

 taken up by the roots, if the soil has the proper character, and 

 thus augment the amount of vegetable products. 



14. Similar must be the conclusion in respect to ammonia as 

 the food of plants, admitting the adequate amount of this sub- 

 stance to have been at first created and throwm into the atmo- 

 sphere to supply the wants of the vegetable kingdom, it would 

 long since have been exhausted, without a continual reproduction. 

 But, in the decomposition of animal and vegetable matter by na- 

 tural processes, it is continually reproduced,. Ammonia, absorbed 

 by vegetables, is decomposed into hydrogen and nitrogen; and 

 these elements go to form the different vegetable products. These 

 pass in part to constitute animal matter, and in part fall to the 

 earth to undergo the process of decay. In the decomposition of 

 the matter of urine, night soil, and some other manures, the pro- 

 duction of ammonia is palpable. 



15. Now, unless animal matter is the entire reproductive source 

 of ammonia, which is not universally admitted, there must be a 

 resort for a further supply of this substance, to the decomposition 

 of vegetable matter. 



10. Then, vegetables contain the two elements which compose 

 it, and their union into ammonia is possible and probable. There 



