FOOD FOR LIVE STOCK 45 



supply of nitrogenous salts with which a depleted 

 soil may be restored has until recently been very 

 limited. 



Some readers may recall the prediction made 

 not many years ago by the English chemist, Sir 

 William Crookes, to the effect that the world 

 would presently suffer from a nitrogen famine 

 that would greatly reduce the wheat crop, and 

 perhaps subject the entire race to danger of star- 

 vation. At that time the chief supply of nitrates 

 came from the nitrate beds of Chile; and it had 

 been estimated that in less than twenty years 

 these beds would be exhausted. 



No one then could say just how the need of the 

 agriculturist would subsequently be met. 



But the discovery that leguminous plants 

 extract nitrogen from the air gave partial answer. 



And almost simultaneously a more complete 

 answer was supplied by scientific workers, headed 

 by the Swedish chemist, Professor Christian 

 Birkeland, in association with a practical engi- 

 neer, Mr. S. Eyde, who discovered that it is pos- 

 sible to convert atmospheric nitrogen into nitric 

 acid with the aid of electricity. 



Another method of fixing atmospheric nitro- 

 gen was soon afterward developed in Italy. 

 Thus the inexhaustible sources of the atmosphere 

 were made available. So there is no longer any 



