OF BODIES CONTAINING NITROGEN. 281 



the production of nitric acid only in so far as it is a 

 slow and continued source of ammonia. 



Now it has been shown in the former part of this 

 work, that ammonia is always present in the atmo- 

 sphere, so that nitrates might thence be formed in 

 substances which themselves contained no azotised 

 matter. It is known also, that porous substances 

 possess generally the power of condensing ammonia ; 

 there are few ferruginous earths which do not evolve 

 ammoniacal products when heated to redness, and 

 ammonia is the cause of the peculiar smell per- 

 ceived upon moistening aluminous minerals. Thus, 

 ammonia, by being a constituent of the atmosphere, 

 is a very widely diffused cause of nitrification, which 

 will come into play whenever the different conditions 

 necessary for the oxidation of ammonia are com- 

 bined. It is probable that other organic bodies in 

 the state of eremacausis are the means of causing 

 the combustion of ammonia ; at all events, the cases 

 are very rare, in which nitric acid is generated from 

 ammonia, in the absence of all matter capable of 

 eremacausis. 



From the preceding observations on the causes of 

 fermentation, putrefaction, and decay, we may now 

 draw several conclusions calculated to correct the 

 views generally entertained respecting the fermen- 

 tation of wine and beer, and several other impor- 

 tant processes of decomposition which occur in 

 nature. 



