FOREIGN ENERGY UNNECESSARY IN NITRIFICATION. 215 



of the original quantity. The sequence of reactions goes on in 

 this way and the whole of the ammonia is finally changed into 

 potassium nitrate, provided the liquor contains an excess of 

 potash. 



The transformation of ammonium nitrate into calcium or 

 magnesium nitrates takes place in virtue of similar reactions, 

 with this difference, however, that the double decompositions 

 can take place between ammonium nitrate and the earthy 

 carbonates, especially when the latter are dissolved by carbonic 

 acid (bicarbonates). Magnesium carbonate can also be dissolved 

 in another way, forming a double salt with ammonium carbonate. 

 Notwithstanding these diversities of detail, the general mechan- 

 isms remain the same whether in the case of potassium, calcium, 

 or magnesium nitrates. 



8. Let us now refer nitrification to gaseous ammonia, and 

 dissolved potassium nitrate, without concerning ourselves with 

 the media, and calculate the heat liberated. 



2NH 3 gas + 40 2 + K 2 C0 3 dilute = 2KN0 3 dilute + 3H 2 + 



C0 2 dissolved. This reaction liberates 109*2, and hardly differs 

 from the formation of dilute nitric acid. 



9. In cases where nitrification is not effected at the expense 

 of free nitrogen and oxygen, but at the expense of free oxygen 

 and of a pre-existing nitrogenous compound, such as ammonia, 

 the cyanides, etc., the heat liberated varies with the nature of 

 the said compound; but it is almost independent of the 

 particular nature of the dissolved alkali which takes part in 

 the reaction (potash, soda, lime) ; it is also the same with the 

 various carbonates compared with one another. This results 

 from an observed fact, viz. that the union of the same acid with 

 the various fixed alkalis liberates nearly the same quantities 

 of heat. 



It will be seen from these data that natural nitrification once 

 excited and under the conditions in which it occurs, that is, in 

 presence of alkaline or earthy carbonates, can be effected without 

 the aid of any foreign energy. 



10. It is effected all the easier, however, when this aid is not 

 wanting, seeing that the oxidation of the nitrated or non-nitrated 

 organic principle is developed at the same time as that of the 

 ammonia yielded by those principles, and liberates an additional 

 quantity of heat. This point deserves to be developed. 



The presence of an alkali, free or carbonated, facilitates, as 

 has been said, the absorption of oxygen by the organic principle. 

 Here is another fact which may be accounted for by thermal 

 considerations; for the oxygen of the said principles forms 

 acids, the formation and the simultaneous combination of which 

 with the alkali liberate more heat than the pure and simple 

 formation of the same free acid would do. For example, the 



