J. H. Gilbert— Points in connection with Vegetation. 185 



ha particular was very much the greater, the larger the propor- 

 tion of oxygen in the air. 



In a second set of experiments, he used the soil in a moister 

 condition ; and instead of the experiment in which the air con- 

 tained only 1-5 of oxygen, lie emploved pure nitrogen; and 

 the experiments extended over a period of about six months. 

 In the ease in which the aspirated air contained no nxvyn, 

 the whole of the nitric acid previously existing in the soi'l'dis 

 appeared; but in the other cases there was a considerable for- 



In a third set of experiments, Schlosing determined the 

 nitric acid in the soils, and added known quantities of potas- 

 sium nitrate in a dilute solution. The mixture was enclosed 

 in a flask of several times the capacity of the volume of soil. 

 At the conclusion of the experiment only traces, if any, of gas 

 containing hydrogen and carbon were present in the air of the 

 vessel. The amount of ammonia in the soil increased con- 

 siderably, but in only small proportion to that which the nitric 

 acid would yield. At the end of the first experiment more 

 potassium nitrate was added, and an atmosphere of known 

 volume and composition supplied. At the conclusion of this 

 experiment the soil contained no nitric acid; the amount of 

 ammonia was increased, but again in only small proportion to 

 the amount which the nitrate would yield. There was indeed 

 a loss of total nitrogen in the soil. 



Schlosing concludes that the combustion of organic matter 

 hi the soil is accompanied by a loss of nitrogen: that the com- 

 bustion may be at the cost of the air as in the experiment of 

 B»ussingauit. or at the cost of nitrates, of ferric oxide, or of 

 the oxygen of organic matter, as in his own experiments. 



It will be seen that on this important point of whether or 

 not the soil may acquire combined nitrogen either in the form 

 ol ammonia bv the combination of fret" nitrogen with nascent 

 hydrogen evolved in the decomposition of organic matter in 

 •I'-tct of oxygen, or in the form of nitric acid by the oxyda- 

 tion ,4 free nitrogen, the evidence is. to sav the least, conflict- 

 !»?'• The more recent results of Boussingault, and those of 

 . vould, however, indicate a greater probability of a 

 loss of combined nitrogen, and evolution of free nitrogen. 



Judging of the probabilities by reference to some of the re- 

 sult f ,,, own in\i -t _,iti i~ « think tluit the* are rather 

 aunit thai in iivoi ot the Miopo-itiou that there is any 

 material gain of the kind assumed bv Mulder and Deheram. 

 It may 1 1 ,wc\ ieflv to call ittt it i m some few 



facts which seem to bear upon the point, whether in favor, or 

 otherwise, of the view in question. 



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