OF BODIES CONTAINING NITROGEN. 309 



nese or iron heated to redness, a large quantity of nitrate of am- 

 monia is obtained, if the ammonia be in excess ; and the same 

 decomposition happens when ammonia and oxygen are together 

 passed over red-hot spongy platinum. 



It appears, therefore, that the combination of oxygen with 

 nitrogen occurs rarely during the combustion of compounds of 

 the latter element with carbon, but that nitric acid is always a 

 product when ammonia is present in the substance exposed to 

 oxidation. 



The cause wherefore the nitrogen in ammonia exhibits such 

 a strong disposition to become converted into nitric acid is un- 

 doubtedly that the two products, which are the result of the oxi- 

 dation of the constituents of ammonia, possess the power of unit- 

 ing with one another. Now this is not the ease in the combus- 

 tion of compounds of carbon and nitrogen ; here one of the pro- 

 ducts is carbonic acid, which, on account of its gaseous form, 

 must oppose the combination of the oxygen and nitrogen, by 

 preventing their mutual contact, while the superior affinity of its 

 carbon for the oxygen during the act of its formation will aid 

 this effect. 



When sufficient access of air is admitted during the combus- 

 tion of ammonia, water is formed as well as nitric acid, and both 

 of these bodies combine together. The presence of water may, 

 indeed, be considered as one of the conditions essential to nitrifi- 

 cation, since nitric cannot exist without it. 



Eremacausis is a kind of putrefaction, differing from the com- 

 mon process of putrefaction, only in the part which the oxygen 

 of the air plays in the transformations of the body in decay. 

 When this is remembered, and when it is considered that in the 

 transposition of the elements of azotized bodies their nitrogen 

 always assumes the form of ammonia, and that in this form nitro- 

 gen possesses a much greater disposition to unite with oxygen 

 than it has in any of its other compounds ; we can with difficulty 

 resist the conclusion, that ammonia is the source of the formation 

 of nitric acid on the surface of the earth. 



Azotized animal matter is not, therefore, the immediate cause 

 of nitrification ; it contributes to the production of nitric acid 



