The Fixation of Nitrogen 7 



There exists in the atmosphere, according to a rough 

 approximation, 4,000 billion tons of nitrogen. Over every 

 square yard there are about seven tons of nitrogen. Over every 

 square mile of the earth's surface we have as much free nitrogen 

 which, if converted into nitrates, would manure the lands of the 

 world for a very prolonged period. Crookes demonstrated the 

 fixation of this free nitrogen by passing electric sparks through 

 air enclosed in a specially constructed globe, and showed that the 

 nitrogen was burned and thus converted into oxides of nitrogen 

 which, when absorbed by water or alkali, yielded acids or salts 

 in nitrogen, products ready for use as fertilizers. Crookes 

 pointed out that the experiment might be made the basis of a 

 huge industry destined to solve the great food problem of the 

 world. 



A few years later the first successful nitrate factory was 

 established by Professor Birkeland and Dr. Eyde at Notodden, 

 where the artificial production of nitrates is carried out on an 

 extensive scale. Here an alternating current of 3,000 — 5,000 

 volts is used, and a powerful electric arc is formed between two 

 copper electrodes placed in a stream of air. The electrodes are 

 hollow to permit them being kept cool by a constant stream of 

 cold water. The terminals are placed about, i to i inch apart. 

 The arc is deflected at right angles to the direction of tlie 

 electrodes by means of a powerful electro-magnet, placed in such 

 a way that the terminals of the copper electrodes are in the 

 middle of the magnetic field. A great roaring disc of flame 

 immensely hot forms between the electrodes. The gases from 

 the flame are pumped off and yield according to the method of 

 absorption either alkali salts or calcium salts. The calcium salts 

 may be applied directly, without purification, to the soil as a 

 fertilizer. 



There is another important method called the Haber process, 

 which has been adopted in countries where water power can be 

 easily obtained When a mixture of nitrogen and hydrogen is 

 subjected to sparks from an induction coil combination takes 



