66 F. B. GUTHRIE AND L. COHEN. 



appear that the production of nitrites is due to any process 

 of denitrification, but rather that under the conditions of 

 the experiment (vegetation being absent and the soil undis- 

 turbed) the action of lime is to promote the development 

 of the organisms which convert the ammoniacal soil 

 nitrogen into nitrous acid. 



The figures for ammoniacal nitrogen do not throw any 

 light on this point, for the decrease in ammoniacal nitrogen 

 after liming is undoubtedly largely due to loss of ammonia, 

 the limed soils all giving off a distinct odour of the gas. 

 The figures obtained are however given : — 



Ammoniacal nitrogen in parts per million of soil. 



Unlimed. Limed. Increase or Decrease. 



Clay 8'2 ... 1*0 ... -7*2 



Loam 5*3 ... 1*6 ... - 3*7 



Sand 5*3 ... *8 ... - 4*5 



The fact that there has been no loss of the very soluble 

 nitrites and nitrates would indicate that the diminution of 

 water-soluble potash and phosphoric acid previously noted 

 is not due to percolation through the walls of the pots so 

 much as to conversion into less soluble forms. 



It is our intention to continue these experiments under 

 conditions which will afford more precise information con- 

 cerning the various questions involved. 



