INORGANIC NITROGEN FERTILIZERS' : ioi 



so produced subsequently breaks up, according to the 

 equation : 3HNO 2 = HNO 3 + 2NO + H 2 O. In the wooden 

 tower nitrogen peroxide and nitric oxide, when mixed 

 together in the presence of water and sodium carbonate, 

 behave as if they were nitrogen trioxide, that is, the anhydride 

 of nitrous acid. The reactions are represented by the 

 equation : Na 2 CO 3 + NO + NO 2 = 2NaNO 2 + CO 2 . 



At present little attempt is made to produce free nitric 

 acid from air for sale, but the dilute nitric acid obtained is 

 treated in granite tanks with limestone, and the liquid 

 evaporated, till it reaches a concentration equal to 

 Ca(NO 3 ) 2 . 2H 2 O. It is then run into iron drums, where it 

 sets into a hard mass, in which form it can be exported, or 

 it may be ground up into a coarse powder and filled into 

 wooden casks. The material roughly corresponds to 

 calcium nitrate, with two molecules of water of crystalliza- 

 tion, and a common analysis is nitrogen 13 %, corresponding 

 to anhydrous calcium nitrate 77 %, and 21 % of water, 

 mostly as water of crystallization, and i or 2 % of insoluble 

 matter, consisting of a little iron oxide and aluminium oxide, 

 with some organic matter. In the wooden towers following 

 the nitric acid towers, a mixture of nitrogen peroxide and 

 nitric oxide reacts, producing sodium nitrite, which is used 

 for commercial but not agricultural purposes. In all these 

 methods a very large amount of electrical energy is expended 

 for the production of oxides of nitrogen. Without cheap 

 energy arc furnace methods are quite impracticable. Im- 

 provements are being made in details, so that one may look 

 forward to a future decrease in the cost of this method of 

 manufacture, if not absolutely, at least relatively to other 

 sources of nitrates. 



Ammonium Nitrate. Whilst ammonium nitrate can be, 

 and is, produced from nitric acid, made as described above, 

 and ammonia, obtained from the distillation of coal, yet the 

 high cost of the machinery needed for the direct oxidation 

 of nitrogen is so great that other methods for the synthetic 

 production of nitric acid have been developed. One of the 

 most important of these is the oxidation of ammonia to 



