Experiment 1. Acidity required, 254 parts of CaO per million 

 to neutralise solution. 



Experiment 2. Acidity required, 646 parts of CaO per million 

 to neutralise solution. 



Experiment 3. Acidity required, 1,050 parts of CaO per 

 million to neutralise solution. 



Alkaline Solutions. 



Days. 







3 



7 



10 

 14 

 21 

 28 



Days. 







3 



7 



10 

 14 

 21 

 o« 



Experiment 1. Alkalinity equals 254 parts of CaO per million. 



2. „' 646 



3. „ 1,050 



4. „ 1,400 



It will be seen from the above that the bacteria fix nitrogen 

 in the greatest quantity when the media are neutral or slightly 

 alkaline. In slightly acid media the nitrogen is fixed in less 



