REPORT ON NITRIFICATION. 309 



oxygen, and a metal.* Viewing the subject by the aid of such lights 

 as science affords, the hypothesis which appears to be best in accord- 

 ance with the facts known concerning the combination of oxygen and 

 nitrogen is that propounded by Dr. G. C. Schoeffer, which is based 

 upon that general chemical action by which various bodies assume 

 the elements of water in such a way as to produce salts of am- 

 monia. This action takes place very commonly with those substances 

 which are produced from ammoniacal salts by the separation of the 

 elements of water, and may be effected under the influence either 

 of acid or of alkalies, and sometimes by the action of water alone at 

 a high temperature. 



Nitrous oxide (N 0) will generate the nitrate of ammonia by the 

 assumption of the elements of w^ater; for, by the action on it of water 

 and potash, at an elevated temperature, ammonia is evolved and 

 nitrate of potash formed, showing that there has been a production 

 of nitrate of ammonia and a subsequent decomposition of it by the 

 potash, t Supposing nitrogen to act in the same way, viz: to assimilate 

 four equivalents of water,! it will form nitrate of ammonia, which, by a 

 well known tendency of the nitrates, will pass into the condition of a 

 nitrate. If potash be present, the nitrate of potash will be produced 

 by decomposition of the ammoniacal salt, and the ammonia set free 

 may be itself nitrified. Without going into theoretical discussion, this 

 hypothesis may be alluded to as one arrived at by legitimate analo- 

 gies, and which it would be interesting and useful to test by experi- 

 mental investigations. The foregoing being considered as a brief 

 sketch of the known laws of nitrification and of one or two of the most 

 important speculations on the subject, we may now glance at the 

 various circumstances under which the process goes on in nature on 

 a scale of economic importance. 



II. The most important of the sources of nitre is the nitiferous soil of 

 Hindostan, where the earth in certain districts becomes impregnated 

 with the nitrates of lime and of potash, chiefly the latter. This takes 

 place during the dry season, Avhen the ground, which has been flooded 

 by previous rains, is subjected to uninterrupted evaporation. Du- 

 ring the rains, a large amount of organic matter must be washed down 

 into the earth and there undergo decomposition. 



Now we may suppose that the ammonia rising to the surface under- 

 goes nitrification after the manner pointed out by Kuhlmann,§ or that 

 its oxidation takes place at a considerable depth, in a way similar to 

 that Qf the cases instanced by Dr. Smith. || In either case, the nitrates 



■•'■ A way of trying this would be by modifying the experiment of Cavendish so as to pass 

 the electric spark through perfectly dry air confined in a tube with metallic potassium or 

 its oxide. 



f There are numerous substances which are formed from salts of ammonia by the separa- 

 tion of the elements of water, and which will regenerate the salt by reassuming them. 

 They are known to chemists as amids, anhydrids, or nitryls. 



\ The action consists in the as5umption of the water by two equivalents: of the nitrous 

 oxide in one case, and of the nitrogen in the other. In the case of nitrous oxide it may 

 be represented thus : Ng O^-f-H^ 04=N05NH4 ; and in the case of nitrogen, N.2-f-H404= 

 NO4NH4. 



§ See page 306. 



II See page 307. 



