28 



Agricu Itura I 



this point. He grew plants for one and one-half to five months 

 with no nitrogen supply beyond that in the seeds and the free 

 nitrogen of the air. The seed was sown in a soil composed of 

 ignited pumice stone and the ashes of manure, both having been 

 freed from nitrogen compounds. The plants were grown in a 

 glass jar sealed from the air but in connection with a supply of 

 carbonic acid and were provided also with water free from nitro- 

 gen. At the end of the experiments the nitrogen was determined 

 in the plants and soil. 



The following table gives the results of five of the experiments 

 and the average of the series : 



*A gram is about one-twenty-eighth of an ounce. 



Since the gains or losses of nitrogen are within the limits of 

 experimental error, Boussingault concluded, as a result of his 

 work, that plants cannot use the free nitrogen of the air. 



This work was disputed by Ville, also of France, who grew 

 plants in larger chambers and renewed the supply of air. He 

 criticised Boussingault 's work for the limited amount of air 

 used. Boussingault then proved by further experiments that 

 plants raised under the conditions of his earlier trials only at- 

 tained full development when supplied with assimilable com- 

 pounds of nitrogen. An investigation of Ville 's experiments 

 then showed that his results were vitiated by the presence of 

 ammonia in his apparatus. 



