26 



solution as mon-amino nitrogen. It will be readily seen this con- 

 clusion is incorrect. The mon-amino acid nitrogen as deter- 

 mined represents the sum of the humin and mon-amino nitrogen. 

 It is very unfortunate that this mistake should have been made 

 since this gives us only the actual ammonia and di-amino acid 

 nitrogen for use in comparison with other investigations of the 

 organic soil nitrogen as distributed by acid hydrolysis. Kelley 

 (1914) following details as outlined by Jodidi (1911) has made 

 the same error and the criticisms above apply with equal force to 

 his data. 



It is also extremely unfortunate that investigators should in 

 any case rely upon figures obtained "by difference" for any one of 

 their fractions. It is sometimes permissible to use figures obtained 

 in this manner, for example, in case a determination has been lost 

 and lack of time or other consideration prevents a repetition ; 

 but to constantly use figures obtained in this manner is unscientific, 

 especially, since by this method we have no means of determining 

 how great the experimental error of the method may have been. 



Jodidi (1911) called attention to the fact that in the case of 

 protein substances the distillation of the hydrolyzed protein with 

 magnesium oxide gives pure ammonia. This, however, may not 

 hold true for the hydrolyzed portion of soils, since some protein 

 substances through decay yield organic bases. It has been shown 

 by Bocklisch (1885) that dimethyl amine is formed through putre- 

 faction of fish, and trimethylamine has been produced by the 

 putrefaction of wheat flour and fish. The bases putrescine and 

 cadaverinc result from the decay of organic substances under cer- 

 tain conditions. It is possible for certain di-amino acids to be- 

 come transformed into di-amines, as for example, arginine can be 

 decomposed into urea and ornithine through bacterial activity. 

 These processes can be expressed by the following equations : 



NH 2 -C(NH)-NH-CH 2 -(CH 2 ) 2 -CH(NH 2 )-COOH + H 2 0- 



Arginine 



NH 2 



Hs-CHr-CH^CH (NH : )-COOH+C=O 



l 



Ornithine .NH, 



Urea 

 NH,,-CH 2 -CH,-CH a -CH(NH 2 )-COOH -- > 



Ornithine 



CO 2 +NH^CH,-CH 2 -CH,-CH 2 -NH 2 

 PUtrescine 



Jodidi found that the ammonia obtained by distilling the 

 evaporated extract of the soil with magnesium oxide was actually 

 pure ammonia, thereby establishing the absence of any volatile 

 organic bases ; but that the phosphotungstic acid precipitate and the 

 filtrate from that precipitate did not represent di-amino and mon- 

 amino acids only. 



In order to find out how much of the di-amino and mon-amino 

 nitrogen actually belonged to di-amino and mon-amino acids, the 

 solutions were subjected to analysis by the formaldehyde-titration 



