284 



AERATION AND 



Sect. XII. i 



of it, as the latter belongs to the refpiratlon rather than to the nutri- 

 tion of vegetables. 



When atmofpheric air is 



mprifoned in the cavities of th 



to 



furface, which mud be 



foil by 



the foil is reduced 

 called pulverizatioi 



th 



quantity, wh 



e 



ry fmall fragments, which has been 

 it is the leaft prefTed down by animals 



tramphng on it, it more readily unites, I beheve, with the materials 

 above mentioned than in its free flate; which is probably effedled by 

 double or triple chemical affinities. 



For this atmofpheric air confifts of oxy 



and 



matter of h 



f the h 



which 



{ions th 



of the atmofpl 



oxy 



fluid 

 and 



ft uncombined in the form of safles 



a 



be attracted from them by any oth 



they are confined 



in the cavities of the foil, they may by their nearer approach to each 

 Other combine into nitrous acid ; or the oxygen may in its fluid ftate, 



> 



not in its aerial one, more readily unite with carbon ; and form a 



fluid, not an 



carbonic acid : which we believ 



be of fo 



much confequence in the growth of plants, as fhewn in Sed. X. 4. 



r 



Add to this, that if any putrefa61:ive procefs be proceeding, where 

 atmofpheric air is thus imprifoned in the cavities of the foil, and by 

 the lofs of its heat is converted from a gas to a fluid ; that the azote 

 may unite with the hydrogen of the decompofing water, or contri- 

 bute to decompofe it ; and thus to form volatile alkali, which like 

 the nitrous acid, may cither'during the procefs of its formation, or af- 

 ter it is fornded, be of efFe£lual fervice to vegetation, at the fame time 



the oxygen given out from the decompofing water may contribute 

 like that of the atmofphere to produce carbonic, nitrous, or phofpho- 

 ric acids ; and thus to render carbon, phofphorus, and the bafis of 

 nitre, capable of being abforbed by vegetable ladeals. 



Where atmofpheric air is confined along with water, I well re- 



member from experiments I made 



o "& 



by inverting a bottle fill 



ed with air in a jar of water, that the bulk of the 



was in 



fome 

 days 



