47 



every square inch of the earth's surface : that contains 12 lbs. of nitrogen 

 at 1 6c. ; very nearly $2 per square inch or $288 per square foot. If 

 we calculate at these rates the value of the atmospheric nitrogen resting 

 upon a square acre it amounts to twelve and a half million dollars and 

 on a farm of 100 acres one thousand two hundred and fifty millions. 

 It would be quite interesting if we were to give a history of the attempts 

 that have been made to realize or fix this nitrogen and get it into the 

 form of ammonia, nitric acid or cyanogen. But the chemists have all 

 failed to do this economically and the only person who has it in his 

 power to utilize it to a certain extent is that humble individual the 

 farmer. 



For nearly a century and a quarter the question of the utilisation 

 of nitrogen by plants has been a subject of controversy among scientific 

 men. It was the famous Priestly who began it in 1 7 7 1 . He and, 

 a few year's later, Ingenhous pointed out that plants are able to 

 assimilate very appreciable quantities of nitrogen from the air. Saussure 

 denied this, so did Woodhouse and Sennebier, all of them basing 

 their conclusions upon experiment. The famous Liebig also wrote on 

 the same sides. Then the question slept until 1851 when Boussingault 

 renewed the controversy and both he and George Ville from their 

 experiments maintained the affirmative side of the discussion. A com- 

 mission of the Academy of Paris took their side, but later Cloez, Mene, 

 Hartung and Gunning came to an opposite conclusion. In 1861 

 Lawes, Gilbert and Pugh ranged themselves on the negative side, but 

 Bretschneider two years later made experiments with lupins and dwarf 

 bean plants obtaining most positive proof of the assimilation of 

 atmospheric nitrogen. Perhaps the conflicting conclusions previously 

 arrived at had been owing to a want of sufficient care in the observa- 

 tions made on different sort of plants. In any case Bretschneider's results 

 only confirmed what was known about the cultivation of the papillion- 

 aceos away back in the time of the Romans. W. Strecker has disin- 

 terred a passage in Pliny (Natural History : Book XVIII.) of 

 which this is a translation ; " Lupins, Lentils or Pulse require so little 

 manure that they in fact replace it ; Vetches make the land 

 fertile. Corn should be sown where previously lupins, vetches 

 or beans have stood, because these only make the land more 



