830 



and grouiul bone was mixed with nitrogen-free gypsum, with kainit, 

 and with pure calcium carbonate. The materials in each trial were 

 thorouj^lily ventilated. The sei>arate trials lasted from 114 to li'l 

 days. In each case the materials were inoculated with a drop of mil 

 extract. The results of this series of exi)eriments are summarized as 

 follows: The two superphosphates allowed no ammonia to escape from 

 the fermenting material ; the superphosphate gjTJSum and pure gypsum 

 sufficed to save considerable amounts of ammonia from loss, but far 

 from the whole. Kainit retained the ammonia better than sui»er})h()s- 

 phate gypsum or pure gypsum. The calcium carbonate was of no use 

 in preventing the escai)e of ammonia, if it did not actually increase the 

 amount generated. Another point of interest is that where the super- 

 phosphates of suiierphosphate gypsum were used no free nitrogen 

 escai>ed, although thist(»ok i)lace in the other c»ases. and especially with 

 kainit. 



The results of experiments l>y the author on jieas, although numer- 

 ous root tubercles were formed, gave no evid«*nce of The fixation of 

 atmospheric nitrogen by bacteria. 



Another noticeable indication fn)ni the results of a series of exi>eri- 

 ments was that unsterilized soil possessed the ability to <'ond>iue 

 hydrogen and oxygen, a proi>erty which is believed to be in all proba- 

 bility <lue to the a<-tion of microorganisms, since the jtrocess was 

 clu'cked by chloroforming the cultures. 



The princii)al ])oints brought out in tlnse investigations are sunmi;v- 

 rized by the author as follows: 



(1) In the decay <»f nitrogenous substances the loss of free nitrogen 

 can occur independently of the formation of nitric acid; while in i>utre- 

 faction under exclusion or i)artial access of air this tloes not take place. 



(2) It remains to be decideil whether or not a loss of free nitrogen 

 occurs in the nitrification of ammonium sails under thomugh ventilation. 



(3) Enrichment of the soil with combined nitrogen by the fixation of 

 this element from the air takes place not only in soils poor in nitrogen, 

 as Berthelot states, but also in materials which ar«' rich in nitrogen. 



(4) Sui>erphosphat*>s are excellent materials tor the conservation of 

 barnyard manure. NN hen thes«' ar«' used in sufficient amount and by 

 free ac<M»ss of air there is no loss either from the volatilization of 

 ammonia or escai)e of free nitrogen. 



(5) Superphosphat*' gypsum is inferior to plain superphosphates for 

 the conservation of nnmures. Its retentive power lor ammonia is much 

 h'ss, but this material also prevented the escape of free nitrogen. 



(6) (iypsum and kainit are inleri(U- jireservatives to the nniterials 

 mentioned above. Although their ability to retain amnionia, esi)e- 

 cially in the moist fermenting substances, is not inconsiderable, an 

 escape of nitrogen is to be fean'd by free access of air. 



(7) L'nsterilized soil after passing through the process of decay 

 showed the ability to unite hydrogen and oxygen. This wa« probably 

 due to bacteria. 



