214 ORIGIN OP THE NITRATES. 



the oxygen of the air, at the ordinary temperature, with the aid 

 of time, and without that of the microbes. 



Large flasks full of air, well closed, and exposed to a 

 moderate light in presence of potash and its dissolved carbonate, 

 were employed. There was also introduced simultaneously 

 with the alkalies a small quantity of oxidisable substances, 

 naturally indicated for the purpose, such as glucose, and 

 essence of turpentine. But no nitre was obtained even after 

 several months (March to June, 1871). In spite of these 

 negative trials, the oxidation of ammonia during nitrification 

 cannot be questioned, but the conditions attendant upon it are 

 only known since the already cited experiments of Schloesing 

 and Miintz. 



7. It will be interesting to further examine the integral trans- 

 formation of ammonium nitrate into potassium nitrate. It has 

 been stated, in fact, that ammonia could yield at first, in becom- 

 ing oxidised, ammonium nitrate. It can further be shown that 

 the whole of the nitrogen contained in this salt passes to the 

 state of potassium nitrate. 



Two phases manifest themselves during this change. 

 The first transformation produces potassium nitrate and 

 ammonia, finally oxidisable. This transformation is effected, 

 both in nature and in the laboratory, by dissolved potassium 

 carbonate. The double decomposition between the two salts, 

 separately dissolved in equivalent proportions, gives rise, accord- 

 ing to the author's experiments, to a noteworthy thermal 

 phenomenon; that is, to an absorption of 3 Calories per 

 equivalent. This phenomenon shows that the potassium 

 carbonate is changed into ammonium carbonate in the liquor ; 

 since the formation of the latter salt by means of the dissolved 

 acid and the dissolved base, liberates far less heat than that of 

 the potassium carbonate. 1 



Now the ammonium carbonate thus formed in the solution 

 disappears by reason of the evaporation of the liquor, or even 

 by the mere fact of the diffusion of carbonic acid and ammonia 

 into the atmosphere ; so that there remains nothing at the end 

 but potassium nitrate, either in the liquor concentrated by 

 evaporation, or in the efflorescent residuum which this liquor 

 yields by spontaneous evaporation. 



The ammonia, on the other hand, after having been brought 

 to the gaseous state, is separated from the carbonic acid, owing to 

 the diffusion of the two gases into the atmosphere ; it is oxidised 

 afresh under the 'influence of the same causes, whichever they 

 may be, that have already changed the half of this base into 

 nitric acid. The other half becomes in its turn ammonium 

 nitrate, and the latter body again reproduces ammonia by the 

 same mechanism, but it does not reproduce more than a quarter 



1 " Essai de Mdcanique Chimique," torn. ii. p. 717. 



