AGRICULTURAL ANALYSIS 



year 730,000 kilograms of monohydrate nitric acid. The success 

 of this enterprise, which has been so anxiously awaited throughout 

 the whole world, should lead the farmers of the world to enter- 

 tain the hope that even if the stores of nitric acid in Chile and 

 other localities are exhausted there can be created a supply of 

 this material, which may be said to be unlimited, obtained from 

 the air and offered from an inexhaustible source, not only for 

 agricultural needs, but also other industrial needs of man. 



It is not likely that this process of Birkeland and Eyde has 

 yet reached its limit of perfection. There is no reason why 

 some similar process might not be conducted in connection with 

 the great waterfalls of this country, which would lead to a sup- 

 ply of nitric acid even at a lower price than can now be secured 

 from natural stores. 



277. Absorption of Nitric Acid and Concentration of the Product. 

 This subject is discussed still further by Howies, espe- 

 cially in regard to the direct oxidation of nitric acid in the air by 

 means of electric discharges and the production of nitric acid 

 therefrom without the intervention of the calcium compounds. 

 The conclusions reached by Howies in regard to this method 

 of producing nitric acid are as follows : 80 



After leaving the furnace, the air contains about two per cent. ' 

 by volume of nitric oxid, which becomes rapidly converted, by 

 means of the excess oxygen present into nitrogen peroxid. 

 The mixed gases then pass on to absorption towers, which present 

 no special features of construction and down which water or 

 dilute acid flows. In the case of the last tower, milk of lime is 

 used, as it is difficult to absorb the last traces of NO 2 by means 

 of water alone. By this process there is obtained an acid of 

 not more than 50 per cent, strength. 



The preparation of a concentrated nitrous-free acid from the 

 nitrous gases constitutes one of the most serious problems in 

 connection with this process. The reaction represented by this 

 equation, viz., 2NO2-f-O-j-H 2 O=2HNO 3 , does not take place 

 in the absorption towers; such an equilibrium appears to exist 

 only in the gaseous state. On condensation the right-hand side 

 80 Electrochemical and Metallurgical Industry, 1907, 5 : 358. 



