NITROGEN PRODUCTS 129 



4. In this connection there should be briefly described the 

 process referred to above for the conversion of ammonia into 

 nitric acid. This consists in passing a mixture of air with 

 about ten per cent, of ammonia gas over red-hot platinum 

 gauze, whereby 90 per cent or more of the ammonia is con- 

 verted into nitric oxide, in accordance with the equation 



4 NH 3 + 50 2 = 4 NO + 6 H 2 O. 



The gases are then cooled and passed through absorption 

 towers, whereby the nitric oxide is converted into dilute nitric 

 acid through the occurrence of the chemical changes described 

 in the preceding paragraph. 



From a technical standpoint, this was the " state of the art " 

 just before the war; but the commercial development of the 

 various processes had been limited, and there were many diffi- 

 culties in their rapid installation in this country. To appre- 

 ciate this, let us briefly review the industrial status of nitrogen 

 fixation at that time, and the economic factors involved in the 

 different processes. 



The cyanamide process requires as raw materials mainly 

 pure limestone, coke, and nitrogen (obtainable from liquid 

 air). The synthetic process depends primarily on cheap coal, 

 but it demands elaborate machinery and highly skilled labor. 

 The arc process makes its product directly from ordinary air, 

 but it requires for its economic operation cheap and abundant 

 water-power. As the power requirement was a vital factor 

 in this country, the following quantitative statement in re- 

 gard to it is of interest. For the fixation of one ton of nitro- 

 gen about 10.5 horse-power years are used in the arc process; 

 2.2 in the cyanamide process, and 0.5 or less in the synthetic 

 ammonia process. 



The arc process was being operated on a large scale in Nor- 

 way, where the water-power needed in great quantity for this 

 process is available at very low cost. It had been introduced 

 also in other countries, but only in a small way. The cyana- 



