Source of Carbon and Nitrogen in Plants and Animals. 365 



■would be continually drawing from the atmosphere a constituent so so- 

 luble in water, and thus presenting it in a state of much greater concen- 

 tration. 



What the amount of nitrogen existing in all the plants and animals, 

 either living or preserved from decay, throughout the globe, may be, it 

 would be extremely difficult to determine ; but admitting Liebig's prin- 

 ciples, it will follow, that the amount of ammonia actually existing in the 

 air will represent the average quantity which, at each moment of time, is 

 disengaged from the organic matter of all kinds undergoing decompo- 

 sition. 



The quantity of ammonia present in the atmosphere under existing cir- 

 cumstances will, therefore, bear the same ratio to that required for the 

 maintenance of the whole animal and vegetable creation taken together, 

 as the amount of organic matter, at any given time, undergoing decom- 

 position, does to that in a state of life, or of preservation from decay. 

 Now, it may be collected, I think, from Liebig's statements, that a pound 

 of rain water sometimes contains as much as |th of a grain of ammonia, 

 or about 35 5 5ii th part. Could we tell, therefore, the proportion which the 

 quantity of organic matter undergoing decay bears to that in a living or 

 sound condition, we might obtain the means of estimating whether the 

 whole amount of nitrogen existing throughout the globe, if it were at 

 once diffused through the atmosphere, would not communicate to it de- 

 leterious qualities. 



I have said that the onus probandi ought to rest with those who pro- 

 pound the last-mentioned hypothesis ; because, undoubtedly, a presump- 

 tion would seem to exist in favour of the view for which I have myself 

 contended, from our having direct evidence that the evolution of these 

 gases from the interior of the globe is proceeding continually. Hence, 

 it seems natural to attribute to a phenomenon at once so constant and so- 

 general, some end in the economy of nature, and to suppose it to have 

 been going on, like the volcanic processes which produce it, without in- 

 terruption, from the beginning of time. 



Granting, then, what upon Liebig's principles seems most consistent 

 with analogy, namely, that the ammonia, no less than the carbonic acid 

 which formed the food of the first plants, has been produced, not by pro- 

 cesses of animal decay, but by such as were proceeding within the globe 

 prior to the creation of living beings, — the notion of a slow and continu- 

 ous disengagement of both compounds, from the earliest period to the 

 present time, will be received, perhaps, as at least the most probable 

 mode of account for their unfailing supply. Whilst it relieves us from 

 the difficulty of supposing the atmosphere surcharged with these gases at 

 any one period, it suggests to us, at the same time, sublime and interest- 

 ing views of the arrangements of the Deity, in thus having made all things- 

 subservient to one common end, and having ordained that the mighty 

 agents of destruction which exist in the bowels of the earth should mi- 

 nister, like the malignant genii of some eastern fable, to the wants and 

 necessities of the living beings which He has placed upon its surface. 



VOL. XXX. NO. LX. APRIL 1841. A a 



